PRODUCING - Alabama Cooperative Extension System

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PRODUCING - Alabama Cooperative Extension System

CIRCULAR ANR-327

PRODUCING

Channel Catfish Fingerlings

ALABAMA COOPERATIVE EXTENSION SERVICE

AUBURN UNIVERSITY

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Extension Service

AUBURN UNIVERSITY


CIRCULAR ANR-327

PRODUCING

Channel Catfish Fingerlings

CATFISH HATCHERIES range from relatively

simple, open-pond spawning systems to complex

systems where eggs are incubated in troughs, depending

on the size and purpose of the operation.

Private hatcheries supply channel catfish fingerlings

for commercial food fish production, recreational

fee-fishing and home-use. Some hatcheries

sell fingerlings to other producers, while

others limit their operations to supplying their

own needs. A careful study of the market should

be conducted before investing in catfish fingerling

production to avoid losses caused by insufficient

demand.

Whatever the size or purpose of the operation,

there must be a sufficient supply of good quality

water and the soil and terrain must be suitable

for pond construction.

Success in fingerling production ca,lls for

healthy, disease-free catfish brood stock, suitable

ponds for holding brood stock and, in most cases,

nursery ponds for rearing fingerlings. Commercial

fingerling producers usually have separate

hatchery troughs and tanks where eggs are incubated

and the newly hatched fish, called fry, are

trained to feed before they are stocked into nursery

ponds. Tanks equipped with a dependable

water supply and aeration are needed to hold and

grade fingerlings before shipment. Seines of suitable

mesh size, length and depth and a fish transporter

are needed to harvest and transport fry

and fingerlings.

- Water of sufficient quantity and quality is critical

for all hatchery systems. The water supply

must be free of contamination such as pesticides.

JoHN JENSEN, Fisheries Specialist, Alabama Cooperative

Extension Service

REx DuNHAM, Assistant Professor, Department of Fisheries

and Allied Aquacultures, School of Agriculture,

Forestry and the Biological Sciences and the Alabama

Agricultural Experiment Station I

JoHN FLYNN, formerly Graduate Aide-Fisheries, Alabama

Cooperative Extension Service

AUBURN UNIVERSITY

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Total alkalinity and total hardness should exceed

20 parts per million, and the pH should range between

6.5 and 8.0. Acid and soft pond water can

usually be corrected with agricultural limestone

to meet these requirements. The conditioning of

well water can be more difficult. Your county Extension

agent can assist in getting your water

tested.

Catfish fingerling production requires more

technical skill and management than producing

food-size fish from fingerlings. The fingerling

producer manages the reproductive behavior of

the catfish brood stock to meet his needs. The objective

is to produce a given number of fingerlings

of a certain size by a specified time. This requires

careful planning, a good understanding of the catfish

reproductive process and selection of an appropriate

production system. Most successful operations

start small and expand as the operator

gains experience.

Brood Stock Selection

Cattle and hog producers recognize that the

quantity and quality of young animals produced

is directly related to the selection and care of

brood animals. Likewise, successful fingerling

Figure 1. Healthy brood fish in the 3 to 10 pound size range are

needed to produce abundant, healthy fingerlings.


producers select the best brood fish and care for

them properly.

Channel catfish generally reach prime breeding

condition in three to four years. Fish less than

four years old are unreliable spawners. Only 20

percent of two-year-old fish can be expected to

spawn. A 40 percent spawning rate for threeyear-old

fish is considered good. Catfish are prime

spawners at four years. With good care, high

spawning rates of about 50 percent are common.

Fish older than six years become too large to handle

easily.

SOURCES AND SELECTION FACTORS

You may want to buy mature fish nearly ready

to spawn rather than waiting for fingerlings to

reach spawning age. The desirable size for brood

fish is 3 to 10 pounds if the fish have had proper

care ( Figure 1 ) .

Probably the best source of brood fish is a

reputable hatchery. However, be careful not to

buy culls. Fish-fanning trade magazines often

carry advertisements for brood stock. Some growers

may have oversized food fish that make good

brood stock. Catfish processors sometimes harvest

large fish and sell them for brood stock.

A void fish recently taken from the wild. They

are often unreliable spawners, and their fingerlings

may grow more slowly and be more susceptible

to disease than fingerlings from established

hatchery stocks.

A void a source having a history of channel

catfish virus disease. This disease can be spread

from the brood stock to all the catfish on your

farm. Check the brooders thoroughly before buying.

The fish should be full-bodied and free of

sores or hemorrhages on the skin. Thin fish may

be old, diseased or underfed.

Be certain that you get enough males and females.

A ratio of about three females for every

two males is a good mix, because one male can

mate with two or more females during a single

spawning season. Although catfish generally produce

offspring in a 50:50 sex ratio, do not take this

ratio for granted in the brooders you purchase.

Determine the sex of each fish you buy.

DETERMINING SEX

Both primary and secondary sex characteristics

are useful in telling males from females. Secondary

characteristics are those not directly related

to reproduction, such as body shape and coloration.

Males are usually larger and have broader

heads than females. As the spawning season

approaches, males become lean, develop large

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Figure 2. Just prior to sp•wnlng, females (left) develop soft, swollen

bellies and have heads narrower than their bodies. Males

(right) have large muscular heads wider than their bodies

and are often darker in color.

Figure 3. To determine sex of brood catfish look at the belly of the

fish. You will see two openings. The opening nearest the

head is the anus. The opening nearest the tail is the genital

opening. On the male (left) the genital opening looks like

a tiny raised nipple. On the female (right) the genital

opening is not raised but is oval. Just before spawning,

the genital opening of the female is often swollen and

reddish.

muscular heads, and sometimes become darker.

Females' heads are narrower than their bodies

when viewed from above. They also develop soft,

swollen bellies (Figure 2).

Always confirm sex by examining the genitals,

the primary sex characteristic. This is particularly

important with young fish and during the

non-spawning season when secondary sex characteristics

are less pronounced. Experienced operators

can sex fish as small as one pound by examining

the genitals.

Turn the fish belly up to examine the genitals.

Two or three openings are present (Figure 3).


The opening nearest the head is the anus, while

the one nearest the tail is the genital opening. The

genital opening of the male is at the end of a

fleshy, nipple-like structure called the genital papilla.

The papilla usually becomes swollen and

rigid as spawning season approaches. The genital

area of the female catfish is oval and flat and has

two openings separated by a small flap of skin. A

slit or groove is located at the head end of the

genital area. A small urinary opening is located

at the tail end. The female genital area often becomes

red, swollen and covered with mucus as

spawning time approaches. Sometimes a pulsating

of the genital area can be seen.

A probe can be used to distinguish the sexes,

particularly in young fish or those not in spawning

condition. A sharp pencil or straw works well.

Hold the fish belly up with one hand grasping the

head and the other hand clasping the fish firmly

at the tail region. This helps immobilize the fish.

With the fish's head just below your chest and

the tail held away from your body, arch the fish's

belly upward. This action causes the male papilla

or female genital slit to become more visible.

Then have an assistant gently slide the probe

over the genital area toward the tail, with the

point leading the probe. If the point of the probe

catches in the genital opening, the fish is a female

(Figure 4).

Brood Stock Management

NUTRITION

Good nutrition is essential to successful spawning.

In warm weather feed a nutritionally complete

diet containing at least 36 percent protein

at about 2 percent of the fishes' body weight daily

(Table 1). Feeding is unnecessary when water

temperature is below 55°F. When water tempera-

Figure 4. Use a probe to distinguish sexes when brood fish ••• not

in spawning condition.

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Ingredient

Soybean meal ( 44% protein)

Ground corn

\i\Theat shorts

Distillers dried solubles

Fish meal

Animal fat

Pellet binder

Dicalcium phosphate

Vitamin premix

Coated vitamin C

Trace mineral mix

Table 1. BRooD FisH DIET.

Analysis:

Total crude protein

Digestible energy

Energy to protein ratio ( kcal/ g),

Percent of total

50.5

14.93

6.0

7.5

15.0

3.0

2.5

0.5

0.75

0.057

0.075

35.6%

2640 kcal/kg

7.3:1.0

ture is between 55°F and 70°F, feed approximately

one percent of the fishes' body weight three

days per week. Estimate the amount to feed by

observing feeding vigor. Offer all the fish will eat

in about 10 minutes during warm weather. Feeding

activity slows greatly with the onset of the

spawning season.

STOCKING DENSITIES

Total weight of brood fish should not exceed

1200 pounds per acre at any time of the year.

Therefore, stock brood ponds at about 600 to 800

pounds of fish per acre. This will allow for weight

gain. For good spawning success they should gain

about 50% of their weight from one spawning season

to the next. Each year unwanted brood fish

should be culled and substituted. By replacing

old fish with young fish the total initial stocking

rate can be maintained.

The most convenient size for a brood pond is

from one to five acres. The extreme temperature

changes in very small ponds can reduce spawning

activity and harm spawned eggs. Ponds over five

acres, on the other hand, are more difficult to

manage.

Be sure to keep brood fish in more than one

pond. This minimizes the risk of losing your entire

stock to a catastrophe such as low oxygen or

disease.

Spawning Management

Spawning ponds should be stocked with not

more than 1200 pounds of brood fish per acre.

Spawning activity usually begins when the water

temperature reaches about 75°F in the spring.

Males nest in hollow logs or similar protected

places in nature. Females are attracted to the

nests and mating begins. Females deposit a layer

of eggs which are fertilized by the male. This


Figure 5. Eggs are laid in a jelly-like mass of up to 4,000 eggs per

pound of female body weight.

process is repeated over several hours until a

jelly-like egg mass of up to two to three pounds,

depending on fish size, is deposited (Figure 5).

Female catfish usually produce from 2,000 to

3,000 eggs per pound of body weight when they

reach five pounds. Smaller females produce up to

4,000 eggs per pound of body weight. The male

guards the eggs, fanning them with his pelvic fins

and tail to force oxygen-rich water into the mass.

USE OF SPAWNING CONTAINERS

Spawning containers should be provided.

Some materials used are milk cans, nail kegs,

earthen crocks, ammunition cans and wooden

boxes. The spawning container must be large

enough to accommodate the brooding pair. The

opening should be just large enough for them to

enter (Figure 6).

Place the containers in one to two and a half

feet of water, one to ten yards apart with the open

end toward the pond center (Figure 7). Mark

each one with a float so that it can be found. Provide

containers for 50 to 90 percent of the brooding

pairs.

Wait until the water temperature reaches 75°F

before putting out the spawning containers. This

discourages early spawning. Gradually move the

containers to deeper, cooler water as the water

warms. However, do not use this technique if the

water becomes stratified by temperature and

oxygen.

Spawning activity sometimes diminishes for

no apparent reason. Lowering the water level

about a foot and rapidly refilling the pond may

encourage additional spawning. Moving the

spawning containers may also stimulate spawning.

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Figure 6. Spawning containers:

a) galvanized ammo can with hinged lid.

b) plastic buckets joined together.

c) wooden box to be staked to pond bottom.


Figure 7. Sp•wning boxes in position.

Considering that not all females spawn and

not all of the eggs, fry and fingerlings survive, estimate

that about 800 to 1,000 fingerlings will be

produced per pound of healthy female brooder.

SPAWNING METHODS

Three methods for spawning channel catfish

allow the fish to spawn naturally in the pond. ·Pen

spawning is used for mating selected pairs.

SPAWNING/REARING PoND METHOD. This approach

requires the least skill, labor and facilities.

However, it is unreliable and not recommended

for commercial operations. Place the spawning

containers in the pond and allow the fish to spawn

naturally. The male hatches the eggs in the container

and the fry remain in the pond.

Drain the pond to harvest fingerlings using a

seine, or trap them as needed, using a technique

described later. The operator using this method

does not know the quantity of fingerlings present

until harvest. Survival of fry is usually poor with

this technique because it is difficult to control disease,

aquatic insects and wild fish that eat fry.

FRY TRANSFER METHOD, OPEN PoND SPAWNING.

The fry transfer method is more productive than

the spawning/rearing pond method but requires

more skill and labor. The newly-hatched fry are

transferred from the spawning container to previously

prepared nursery ponds. Check spawning

containers every three days. When an egg mass is

found, gently pinch off a clump of 6 to 10 eggs

from the edge. Determine the age of the eggs

to predict the hatching date (Table 2).

Allow the male to incubate the eggs. Remove

the fry one day after the predicted hatching date.

The male catfish is capable of inflicting painful

bites to hands and bare feet, so chase him from

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Table 2. EsTIMATING" THE AcE oF CATFISH EGGS.

Egg description

No pulsation

Pulsating motion

Bloody streak

Blood throughout egg

Eyes visible

Eyes visible, embryo turns inside shell

Complete fish visible, no bloody streak

Hatching begins

Estimated age

(water at 78°F)

Less than 24 hours

1 to 2 days

2 to 3 days

3 to 4 days

4 to 5 days

5 to 6 days

6 to 7 days

7 to 8 days

Note: For every 2°F above or below 78°F, subtract or

add one day, respectively, to hatching time.

Source: Howard P. Clemens and Kermit E. Sneed, 1957.

Spawning behavior of the channel catfish Ictalurus

punctatus. Special Scientific Report-Fisheries

No. 219. U.S. Department of Interior, Fish and

Wildlife Service.

the spawning container using a stick or gloved

hand or lift the container gently off the pond bottom

until he exits.

Transfer the fry to a bucket containing pond

water by gently pouring them from the spawning

container. Release the fry into the nursery pond

by slowly submerging the bucket, allowing them

to escape into the pond near a shelter. The spawning

container can be moved to the nursery pond

and left for shelter.

If the water temperature is not the same in

both ponds, the fry must be slowly acclimated to

the nursery pond temperature before stocking.

When temperature differences are more than two

to three degrees, slowly replace water in the

bucket with nursery pond water until the water

temperature is equalized.

EGG TRANSFER METHOD, OPEN POND SPAWNING.

Egg transfer is the most productive of the three

methods but also requires the most skill, labor and

facilities. The fish are allowed to spawn in the

containers as with the other methods, but the eggs

are removed and incubated in a hatchery.

Check the spawning containers every two to

four days. Late morning is the best time, because

most spawning probably occurs at night or early

morning. Checking at this time thus does not interrupt

spawning activity and allows for timely

removal of eggs. Remove eggs immediately after

finding them. Disturbed brood fish may sometimes

eat eggs or dislodge them.

The egg mass sticks to the container floor.

Gently scrape it from the container with a plastic

credit card, kitchen spatula or similar device (Figure

8). Float the egg mass into a bucket and car-


Figure I. Treat egg ma•M• gently.

Figura 9. Spawning pans for mating selected pairs.

ry it immersed in water to the hatchery. Eggs can

be left in buckets in a shaded area for up to 15

minutes, but no longer unless aeration is used.

Eggs must be shielded from sunlight. Egg masses

near hatching must be taken to the hatchery immediately

because they require more oxygen than

young or "green" egg masses.

PEN SPAWNING. Pen spawning, a modification

of the previously described methods, is used mainly

for mating selected pairs. Construct pens next

to the pond bank, using plastic-coated wire or

other non-rusting materials. Mesh should be

large enough to allow water to circulate, but not

so large as to allow brood fish to escape. Mesh

size from one-half to two inches is satisfactory. A

pen 4 X 6 feet is adequate. Adjacent pens can

have common sides, to minimize construction

costs ( Figure 9) .

Place a spawning container and a ready

spawning pair in each pen. The fish should be

about equal in size. Check pens from the bank

daily for welfare of the brooders. Remove females

that are being harassed or injured by the male

fish. Remove the female immediately after spawning

to keep her from being injured or killed by the

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aggressive male. Do not place more than one female

in the pen at a time, as this can lead to fighting

and injury to the females. Eggs can be left

with the male or taken to the hatchery to incubate.

If spawning does not occur in 10 to 14 days,

check the sexes of the pair and exchange brood

fish if needed.

The Hatchery

In maximum-production systems, eggs are

transferred to a special hatchery, and incubated

and the fry started on food before they are

moved into nursery ponds. The hatchery need

not be elaborate. Some of the equipment can be

built by the operator. The critical ingredient is

a water supply of the right quality and quantity.

WATER QUALITY

Water temperature must be between 75°F and

85°F for proper hatching. Because eggs and fry

have high oxygen requirements, maintain oxygen

levels at a minimum of six parts per million. Water

pH must be between 6.5 and 8.0 for best results.

Risk of disease is less if there are no fish in the

water supply. Keep water as clean and free of organic

matter such as algae and decaying leaves as

possible. A water flow of about five gallons per

minute is needed for one hatching trough.

Well water is probably best for use in the

hatchery. It is usually clean and free of disease

organisms. vVell water, however, is generally too

cold for optimum hatching. It can be warmed in

a conventional water heater or stored and warmed

in a small pond built specifically for this purpose.

Well water contains very little oxygen. Splash

it over a cascade or through screens to add oxygen.

Storing well water in a pond before use also

increases oxygen content. Well water with a high

iron content should be aerated in a settling tank or

reservoir pond before distribution to the hatchery.

Some hatcheries receive water directly from

production ponds. Pond water is usually the

proper temperature for incubation, but may present

other problems. Disease organisms can be

introduced to the hatchery from the pond, especially

if fish are present. Algae, suspended mud

particles, and other materials in pond water can

accumulate on eggs and smother them. The oxygen

content of ponds often fluctuates, and low

oxygen levels, two to three parts per million (ppm),

are especially dangerous to fish eggs and fry.

INCUBATION TROUGH CONSTRUCTION

Eggs are commonly incubated in wooden, fiberglass

or metal troughs about 8 feet long, 18 to


24 inches wide and 10 to 12 inches deep. A series

of paddles attached to a shaft are suspended in

the trough (Figure 10). Paddles are spaced to

.allow wire-mesh baskets holding the egg masses to

fit between them. The paddles should reach about

halfway to the bottom of the trough and should

extend below the bottoms of the baskets. Baskets

are made from one-fourth inch hardware cloth

Figure 10. Space paddles so that bukets holding eggs will fit be·

tween them.

Figure 11. Construct baskets of one-fourth inch h.,dwere cloth.

(Figure 11). An electric motor with a gear reduction

attachment turns the paddles at 30 rpm. This

motion gently rocks the egg masses and causes

oxygen-rich water to flow through them. An 8-foot

trough can hold six to eight egg baskets (Figure

12).

Water enters one end of the trough at five gallons

per minute. A standpipe fitted into a drain

at the other end controls water depth. Place window

screen over the standpipe to prevent fry from

escaping.

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Figure 12. An 8·foot paddlewheel trough can hold 6 to 8 baskets

containing 12 to 16 egg masses, depending on water flow

and egg mass size.

DISEASE CONTROL

Bacterial diseases and fungus infections are

constant threats to eggs. The best disease control

is prevention. A clean water supply and frequent

scrubbing and disinfection of troughs and equipment

are essential. Remove debris and egg shells

regularly with a siphon.

Various chemical treatments are routinely

used to prevent or treat bacterial infection (Table

3). Treat the eggs when they are removed from

the spawning container and once or twice daily

until they hatch. Distribute the proper amount

of chemical evenly along the length of the hatching

trough. Check the eggs for egg rot and fungus

and gently shake and turn them over two to three

times daily.

Bacterial egg rot appears as a milky-white

dead patch, usually on the underside and center

of the mass. Remove the infected areas immediately

and continue treating. Change the treatment

every four days to prevent a resistant bacterial

strain from developing.

Fungus grows on infertile or dead eggs. It appears

as a white or brown cotton-like growth

made of many small filaments and can invade and

kill healthy eggs. Fungus can be controlled by

treating with 100 parts per million formalin for

15 minutes. Turn the water off during treatment

but leave the paddles turning. Flush completely

with clean water when treatment time has

elapsed. Do not use the formalin treatment when

eggs are within one day of hatching.

HANDLING SAC FRY

Temperature controls incubation time (Table

2). Sac fry emerge as the eggs hatch, swim

through the screen baskets and school together in

a tight cluster on the bottom of the trough.


Figure 14. Holding boxes should be aerated by spraying water from

above.

Figure 15. A strainer placed in a bucket can be used to collect fry by

siphoning.

ated cylinder containing a pre-measured quantity

of water, taking care not to add any extra water

with the fry (Figure 17). Record the change in

water level when the fry are added. The total

number of fry can be estimated by placing all of

them in a graduated measuring container, recording

the water level change, and then comparing

the two numbers. Use this equation:

Total number of fry =

300 X change in water level with ALL fry

change in water level with 300 fry

For example, a sample you take of 300 fry

raises the water level in a 100-milliliter ( ml) graduated

cylinder from 50 to 62 ml. You will estimate

the total number of fry using a larger, wide-

Figure 16. Boxes made entirely of screen can be used to hold fry Figure 17. Count a representative sample of fry into a gradu•ted

when overhead spray is not used.

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cylinder and measure the change in volume.


Figure 18. Estimate the total number of fry by the change in water

volume in a graduated wide-mouthed container.

mouthed container also graduated in milliliters

(Figure 18). When you add all the fry, the water

level changes from 500 ml to 900 ml. Then:

300 X (900- 500)

Total number of fry=---..:,__----'-

62 -50

300 X 400

or----

12

10,000 total number of fry

FEEDING FRY

Begin feeding the fry when they first swim up

to the surface with their mouths opening and

heads moving back and forth, obviously searching

for food. "Swim-up" usually occurs about

three to four days after hatching. A high protein

diet ( 45 to 50 percent crude protein) with all essential

nutrients should be used. Recent findings

suggest that the protein should consist of about

60 percent fish meal. The food must be finely

ground so the fry can easily consume it. Commercial

fry food is usually available. Other suitable

feeds such as ground trout feed or salmon starter

can be used.

Several feeding techniques are practiced. The

dry food can be lightly sprinkled on the surface

(Figure 19). The fry will eat the portion that

floats. The food can also be moistened, formed

into a doughball and placed in the fry box or

tank. Another technique is to make a slurry and

pour it onto a plastic plate anchored to the bottom

of the fry box or tank. Feeding activity of

fry will keep the feed in suspension where it is

easily consumed.

Whatever the techniques, the fry should be

fed at least six times daily. More frequent feeding

is better. Be careful not to overfeed, how-

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ever, because wasted food will accumulate, causing

poor water quality and fungus growth. Waste

should be siphoned out and tanks and boxes

scrubbed daily. Equipment should be scrubbed

and sterilized with a 1:4,000 formalin in water solution

after each crop of fry.

Water quality in the holding facility determines

the length of time the fry can be held in

the hatchery. Fry may be held for up to 10 days

if good water quality is maintained. Water quality,

in turn, is dependent on such factors as water

flow rate, number of fry held and cleanliness

maintained.

Figure 19. Feed • finely ground feed to fry held in boxes. Siphon

wastes from boxes and tanks daily.

Fry should be eating food before they are

transferred into nursery ponds. They survive

much better in ponds when stocked as large,

strong fry.

Growing Fingerlings

The pond should be prepared to receive the

fry being grown in the hatchery. Pond preparation

is critical for good fry survival. Certain

aquatic insects and fish eat fry and must be controlled.

The "puddle" method of preparing nursery

ponds helps control insects and promotes the

growth of fish food organisms that fry will eat.

Drain and dry ponds thoroughly before stocking

the fry. Fertilize with about 100 pounds per acre

of old fish food, meat and bone meal or similar organic

material just before filling with water. Organic

fertilizer promotes growth of zooplankton,

tiny aquatic animals that are excellent fry food.

Stock the pond on the third or fourth day after the

pond begins to fill. With this method, the fry outgrow

insects and usually no special insect control


Figure 20. Insects that eat catfish fry (left to right): backswimmer,

dragonfly nymph, predaceous diving beetle. Kill back·

swimmers and diving beetles with an oil treatment. Drag·

onfly nymphs breathe with gills and are controlled by

keeping the pond dry until shortly before stocking fry.

is required. However, an independent water supply

such as a well or spring is needed to fill the

pond.

CONTROLLING INSECTS

Treatment to control insects is necessary when

the pond must be filled more than one week before

stocking ( Figure 20) . A common practice is

to spread a mixture of five to eight gallons of

diesel fuel or kerosene mixed with one quart of

motor oil per acre over the pond surface two days

before stocking. The oil film prevents air-breathing

insects from penetrating the surface to

breathe. The effectiveness of this treatment depends

on complete coverage of the pond surface

with oil. Apply oil when there is no wind or just

a light breeze. Continue this treatment for the

first two weeks at four-day intervals. A disadvantage

of this method is that it does not kill gillbreathing

insects. It also depresses oxygen levels

and inhibits zooplankton growth.

STOCKING FRY

Stock the fry while it is cool in early morning.

Gently transfer them in buckets or similar con-

Figure 21. Shelters provide areas for fry to congregate in to aid in

feeding and protection.

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tainers and slowly condition them to the pond by

gradually adding small quantities of pond water

to the fry container. Shelters such as milk cans

or frames covered with black plastic are desirable

in the ponds to improve survival and to provide

areas for fry to congregate, which aids in feeding

(Figure 21).

Stocking density depends on the size fingerlings

desired at harvest. Growth rate depends

primarily on the quantity of food the fry and fingerlings

consume if water temperature is optimum.

With very high stocking densities, it is unsafe

to feed for very long the quantity needed for

maximum fish growth, because of water quality

problems. Table 4 shows the expected fingerling

size for a 120- to 150-day growing season at different

stocking densities. V eTy good management is

needed to attain these yields.

Table 4. EsTIMATED FINGERLING SizE AFTER 120- TO 150-

DAY GROWING SEASON AT DIFFERENT STOCKING

DENSITIES.

Fry stocking density

(fish per acre)

10,000

30,000

53,000

73,000

95,000

120,000

140,000

200,000

300,000

500,000

Average length

(inches)

7-10

6-8

5-7

4-6

3-5

3-5

3-4

2-3

1-2

1

FEEDING FRY AND SMALL FINGERLINGS

Fry and small fingerlings have large appetites

and should be fed frequently, two to three times

daily for the first two weeks. Feed a finely-ground,

40 percent to 45 percent protein diet the first

three to four weeks. Recent studies suggest that

the protein should contain at least 20 percent fish

meal. Switch to small-size crumbles of more than

40 percent protein from four to six weeks of age

and then to a small pellet approximately 3/16

inch in diameter containing 36 percent protein.

Make sure that the particle size is small enough

to be swallowed by the smallest fish so that the

fingerlings grow uniformly. It is better to slightly

overfeed in the early stages to ensure that all

fry get enough food.

As the fingerlings grow, they will eat less food

in proportion to their body weight. Feed according

to Table 5. However, feeding more than 35

pounds of feed per acre per day will increase the

probability of low oxygen problems.


Table 5. SuGGESTED FEEDING RATES FOR DIFFERENT SizE CATFISH AT VARIOUS WATER TEMPERATURES MEASURED AT

ONE FooT DEEP.

Total length in

inches and average

number per pound Percent of body weight to feed daily

Average daily water 65° 67° 69° 7P 730 75° 770 79° 81°

temp. F 0 at 1 foot" -------- - - - ----- %-----------------

3" ( 100/lb) 1.5 2.4 3.6 4.8 6.0 7.2 8.4 9.6 10.8

4" (50/lb) 1.5 1.8 2.7 3.6 4.5 5.4 6.3 7.2 8.1

5" ( 31/lb) 1.5 1.5 2.2 2.9 3.6 4.3 5.0 5.8 6.5

6" (17 /lb) 1.5 1.5 1.8 2.4 3.0 3.6 4.2 4.8 5.4

7" ( 11/lb) 1.5 1.5 1.5 2.1 2.6 3.1 3.6 4.1 4.6

8" (9/lb) 1.5 1.5 1.5 1.8 2.3 2.7 3.2 3.6 4.1

9" (6/lb) 1.5 1.5 1.5 1.6 2.0 2.4 2.8 3.2 3.6

10" (3/lb) 1.5 1.5 1.5 1.5 1.8 2.2 2.5 2.9 3.2

"To obtain the average daily water temperature take temperature morning and afternoon each day and average them.

Both floating and sinking feeds are available.

Sinking feed is less expensive but floating feed allows

observation of the fingerlings. Mixing floating

feeds with the sinking type permits observation

and cuts feed costs.

Feeding activity slows considerably with cool

weather. When water temperature is 45°F to

55°F, feed five- to seven-inch fingerlings about

1.5 percent of their estimated body weight three

days per week. Fingerlings fed over winter (November

to March) in the South will gain from 25

percent to 40 percent of their initial body weight.

Smaller fingerlings need more frequent feeding

during winter. Feed them 1.5 percent of their

estimated body weight six days per week when

water temperature is between 52°F and 55°F and

three days per week when water temperature is

40°F to 52°F. Use Table 5 as a guide for feeding

fingerlings at water temperatures above 65°F.

WEED CONTROL

Aquatic weeds and pond "moss" are undesirable

in fingerling ponds. Harvesting fingerlings

is very difficult if weeds collect in seines. Excessive

aquatic weed growth also depresses oxygen

levels. Stocking 50 to 100 eight-inch grass

carp per acre is an effective weed control measure

in states where they are allowed (Figure 22).

Stock grass carp soon after the catfish fry are

stocked. Many grass carp jump over seines and

usually do not greatly interfere with fingerling

harvest.

DISEASE CONTROL

Diseases can be a serious problem for fingerling

producers. Good management, however, can

prevent many diseases, since many disease outbreaks

are related to fish stress caused by unfavor-

-14-

Figure 22. Grass carp effectively control most weeds in catfish ponds.

able environmental conditions, poor nutrition and

improper handling. When a particular disease is

diagnosed, specific treatments are available.

Some signs of diseases are changes from normal

behavior, reduced vitality, reduced feeding

activity, lazy swimming and open sores. Fish that

appear diseased should be sent immediately to a

laboratory for diagnosis. Laboratories providing

diagnostic services are listed in Appendix 2.

Select only live fish with disease signs for diagnosis.

Dead fish are unusable. Place one or two

of the smallest sick fish into a strong plastic bag.

Put in just enough water to cover the fish. Fill the

bag with pure oxygen if possible and tie securely.

Place the bag in a strong, waterproof box ( styrofoam

is best ) . Pack crushed ice in a separate

plastic bag and place this bag in the box next to

the fish (Figure 23). Ship the sample by bus or

deliver it personally. Call the laboratory to advise

them of the shipment and to provide needed information.


Figure 23. Ship diseased fish in a plutic bag with oxygen and water

packed in a styrofoam container with ice to ensure survival.

The laboratory will infonn you of the diagnosis

and recommend a treatment if needed. Chemical

treatments are generally a last resort and are

recommended when there is no alternative. Table

3 contains chemical treatment recommendations

for common fish diseases. Take every precaution

when applying chemicals. Fish have narrow

tolerance ranges for some chemicals, so very

exact calculations are needed. Determine and

record the volume of all your ponds, tanks and

troughs for reference. Calculating treatment

rates is much faster when this information is readily

available.

Some characteristics of the water may affect

the treatment rates. Analyze your water before

you treat. Copper sulfate, for example, is toxic

to catfish in very soft water. When the water has

less than 20 ppm total alkalinity, do not use copper

sulfate before consulting with a fisheries biologist.

Use a treatment rate of 0.5 ppm when

total alkalinity is between 20 and 50 ppm. Higher

treatment rates are needed in more alkaline water.

Use 1.0 ppm copper sulfate when alkalinity is between

50 and 100 ppm and 1.5 ppm copper sulfate

when alkalinity is between 100 and 150

ppm. Water of 150 to 200 ppm alkalinity needs

2 ppm copper sulfate. Copper sulfate is ineffective

in water of alkalinity greater than 200 ppm.

Potassium permanganate is commonly recommended

for treating some external bacterial and

parasitic diseases. It is an oxidizing agent that

reacts with organic matter in pond water. The

portion of chemical that reacts with organic matter

is ineffective in controlling disease.

As a rule of thumb, apply the recommended

rate of potassium permanganate and watch for

the water to change color. If the water turns

-15-

brown within 12 hours after treating, the full rate

must be applied again.

Ichthyopthirius, commonly called "Ich," is

probably the biggest killer of fingerling catfish.

"Ich" is a tiny parasite that burrows into the fish's

skin and gills, causing white, pin-head-sized spots

which can easily be seen. This disease is most

common in the spring when water temperature is

between 68°F and 77°F; however, it can appear

at any time of year. Treat "Ich" using 25 ppm

formalin ( 37 percent formaldehyde) every three

days when the water temperature is between 60° F

and 70°F, every seven days when the temperature

is between 50°F and 60°F and every 14 to 21 days

when the temperature is below 50°F.

Chemicals used for treating diseases should be

thoroughly mixed and evenly distributed from a

boat. Always wear protective clothing and follow

label instructions carefully.

Potassium permanganate, formalin and copper

sulfate kill algae in ponds, which may cause low

oxygen problems. Be sure to have emergency

aeration equipment readily available when treating

with these chemicals.

Channel catfish virus disease ( CCVD) is a

disease that affects only fry and fingerling channel

catfish when the water is warmer than 70°F. Signs

of this disease are pop-eye, hemorrhaging at the

base of the fins, swollen belly and pale gills. Behavior

includes erratic swimming and :floating

head-up. There is no cure for this disease, so prevention

is essential. Isolation of infected brood

stock is important because exposed adults are believed

to be carriers.

WATER QUALITY

Good water quality is essential to producing

healthy fingerlings. Low oxygen is by far the most

common water quality problem. Oxygen levels

should be above four ppm at all times for fingerlings

to grow well. Growth can be severely slowed

when oxygen remains below three ppm for long

periods. Stress caused by these conditions can

also lower resistance to disease.

Algae, the tiny plants that give water a green

color, produce oxygen during bright daylight and

put it into the water. However, no oxygen is produced

at night, and respiration of fish, algae and

decaying wastes take oxygen from the water.

When temperatures are high and fish are growing

rapidly, more oxygen may be taken out at night

than is being produced during the day. Also;

cloudy days may reduce the amount of oxygen

produced. The result can be dead fish. The probability

of low oxygen levels increases with higher


Figure 24. Test equipment: a) Dissolved oxygen chemical test kit.

b) Dissolved oxygen meter,

feeding and stocking rates. Dissolved oxygen

levels should be monitored daily at dawn and dusk

during warm weather. Oxygen test kits and more

expensive oxygen meters are commercially available

and are a worthwhile investment for the serious

producer (Figure 24). Records kept of daily

oxygen readings in each pond can help producers

predict low oxygen problems.

Emergency aeration equipment must be

readied when low oxygen is expected. Probably

the most effective device, especially for ponds

larger than two to three acres, is the tractor-driven

paddlewheel aerator. It quickly creates a zone of

oxygen-rich water where fingerlings concentrate.

The electric, surface-spray aerators are effective

for emergency use only in small ponds (Figure

25).

Some compounds found in water at relatively

small concentrations are potentially harmful to

fish. Copper and zinc are extremely toxic to fish.

Galvanized equipment such as pipes, containers,

-16-

screens and tanks may give up enough zinc to be

toxic. Copper from pipes and other eqmpment

can also be toxic to fish. Metal toxicity can be

particularly troublesome in the hatchery. Use

plastic pipe, buckets and other equipment wherever

possible.

Catfish are very sensitive to chlorine. Water

from city supplies must not be used in the hatchery,

to haul fish or to fill ponds unless it is dechlorinated

with sodium thiosulfate at 7 ppm for each

part per million chlorine. Most municipal water

supplies are chlorinated with less than 2 ppm.

Pesticides from cultivated watersheds may be a

problem in ponds that receive runoff. Some pesticides

are much more toxic to fish than others.

Prevent contamination of the water supply.

Harvesting and Handling

HARVESTING

Harvesting fingerlings is easier in ponds that

have clean, firm bottoms. Weeds and algae catch

in seines and make them difficult to pull. Fingerlings

also become entangled in the debris and are

injured. A mud-line should be used to prevent

the seine from digging into soft, mucky bottoms.

The mud-line also limits muddying the water

which stresses fish, especially during warm weather

(Figure 26).

About 75 percent of the fingerlings can be removed

by trapping them while they feed. Stretch

a 100- to 200-foot long seine parallel to shore at a

Figure 25. Aerators: a) Electrical spray-type surface aerator.

b) A paddlewheel aerator.


Table 7. LENGTH AND WEIGHT RELATIONSHIPS FOR VARIous

SIZE CHANNEL CATFISH FINGERLINGS.

Fish length

(inches)

1

2

3

4

5

6

7

8

9

10

Average weight

of 1,000 fish (lbs)

0.7

3.5

10

20

32

60

93

112

180

328

Number of

fish per pound

1500

286

100

50

31

17

11

9

5.5

3.1

and weighed. The weight of fish per thousand is

calculated from the sample. All the fingerlings

are weighed as they are loaded into the transporter

and the total number is estimated from

the average weight of the individual samples. For

example, two samples are taken of 200 fish each.

Sample weights are 10 ounces and 12 ounces. You

then have 22 ounces or 1.4 pounds per 400 fish,

or 3.5 pounds per 1,000 fish.

The total weight of all the fingerlings divided

by 3.5 pounds equals the total number in thousands

of fingerlings. From Table 7, the average

fingerling length is between three and four inches.

Unless the fish are uniformly graded, estimating

the average length from the table is unreliable.

HAULING

Fingerlings may be hauled long distances with

proper equipment and care. Use fresh, clean

water in the fish transporter. Hauling tanks

should be equipped with electric agitators to oxygenate

the water and to release waste gases such

as carbon dioxide and ammonia. Hauling tanks

should not be deeper than 30 inches when only

agitators are used. An air blower or bottled oxygen

is needed with deeper tanks or with exceptionally

heavy fish .loads. Bottled oxygen is also

a good backup in case the agitators fail (Figure

29).

Bottled oxygen is released into the water

through porous diffusers. Small bubbles transfer

more oxygen into the water than large bubbles. A

combination of small bubbles from bottled oxygen

and mechanical agitation achieves high oxygen

transfer and good waste gas removal, respectively.

The number of fingerlings that can be safely

hauled depends mainly on the volume of the transporter,

the efficiency of the aeration system, the

water temperature, the length of haul, and size

and condition of the fish. Hauling tanks should

be insulated to prevent water from over-heating,

particularly on long trips. Reduce the load given

Figure 29. Hauling tanks should always be equipped with bottled

oxygen in case other aeration systems fail.

Table 8. LoADING RATES FOR TRANSPORTING VARIOus SizE CATFISH

Fish size Transport time (hours)

(Number per pound) 8 hrs. 12 lm. 16 hrs.

- Loading rates (pounds fish/gal)

1 6.3 5.6 4.8

2 5.9 4.8 3.5

4 5.0 4.1 3.0

50 3.5 2.5 2.1

125 3.0 2.2 1.8

250 2.2 1.8 1.5

500 1.8 1.7 1.3

1000 1.3 1.0 0.7

10000 0.2 0.2 0.2

Rates given are for water temperature at 65°F and assume proper equipment and aeration. Reduce rates by 25 percent

for each 10°F rise in temperature.

-18-


Figure 23. Ship diseased fish in a plutic bag with oxygen and water

packed in a styrofoam container with ice to ensure survival.

The laboratory will infonn you of the diagnosis

and recommend a treatment if needed. Chemical

treatments are generally a last resort and are

recommended when there is no alternative. Table

3 contains chemical treatment recommendations

for common fish diseases. Take every precaution

when applying chemicals. Fish have narrow

tolerance ranges for some chemicals, so very

exact calculations are needed. Determine and

record the volume of all your ponds, tanks and

troughs for reference. Calculating treatment

rates is much faster when this information is readily

available.

Some characteristics of the water may affect

the treatment rates. Analyze your water before

you treat. Copper sulfate, for example, is toxic

to catfish in very soft water. When the water has

less than 20 ppm total alkalinity, do not use copper

sulfate before consulting with a fisheries biologist.

Use a treatment rate of 0.5 ppm when

total alkalinity is between 20 and 50 ppm. Higher

treatment rates are needed in more alkaline water.

Use 1.0 ppm copper sulfate when alkalinity is between

50 and 100 ppm and 1.5 ppm copper sulfate

when alkalinity is between 100 and 150

ppm. Water of 150 to 200 ppm alkalinity needs

2 ppm copper sulfate. Copper sulfate is ineffective

in water of alkalinity greater than 200 ppm.

Potassium permanganate is commonly recommended

for treating some external bacterial and

parasitic diseases. It is an oxidizing agent that

reacts with organic matter in pond water. The

portion of chemical that reacts with organic matter

is ineffective in controlling disease.

As a rule of thumb, apply the recommended

rate of potassium permanganate and watch for

the water to change color. If the water turns

-15-

brown within 12 hours after treating, the full rate

must be applied again.

Ichthyopthirius, commonly called "Ich," is

probably the biggest killer of fingerling catfish.

"Ich" is a tiny parasite that burrows into the fish's

skin and gills, causing white, pin-head-sized spots

which can easily be seen. This disease is most

common in the spring when water temperature is

between 68°F and 77°F; however, it can appear

at any time of year. Treat "Ich" using 25 ppm

formalin ( 37 percent formaldehyde) every three

days when the water temperature is between 60° F

and 70°F, every seven days when the temperature

is between 50°F and 60°F and every 14 to 21 days

when the temperature is below 50°F.

Chemicals used for treating diseases should be

thoroughly mixed and evenly distributed from a

boat. Always wear protective clothing and follow

label instructions carefully.

Potassium permanganate, formalin and copper

sulfate kill algae in ponds, which may cause low

oxygen problems. Be sure to have emergency

aeration equipment readily available when treating

with these chemicals.

Channel catfish virus disease ( CCVD) is a

disease that affects only fry and fingerling channel

catfish when the water is warmer than 70°F. Signs

of this disease are pop-eye, hemorrhaging at the

base of the fins, swollen belly and pale gills. Behavior

includes erratic swimming and :floating

head-up. There is no cure for this disease, so prevention

is essential. Isolation of infected brood

stock is important because exposed adults are believed

to be carriers.

WATER QUALITY

Good water quality is essential to producing

healthy fingerlings. Low oxygen is by far the most

common water quality problem. Oxygen levels

should be above four ppm at all times for fingerlings

to grow well. Growth can be severely slowed

when oxygen remains below three ppm for long

periods. Stress caused by these conditions can

also lower resistance to disease.

Algae, the tiny plants that give water a green

color, produce oxygen during bright daylight and

put it into the water. However, no oxygen is produced

at night, and respiration of fish, algae and

decaying wastes take oxygen from the water.

When temperatures are high and fish are growing

rapidly, more oxygen may be taken out at night

than is being produced during the day. Also;

cloudy days may reduce the amount of oxygen

produced. The result can be dead fish. The probability

of low oxygen levels increases with higher


DISEASES

Principal Diseases of Farm-Raised Catfish. J. A.

Plumb, editor. 1979. Southern Cooperative Series

No. 225. Alabama Agric. Exp. Sta., Auburn

University, AL.

Textbook of Fish Diseases. 1970. Erwin Amlacher.

T.F.H. Publications, Jersey City, NJ.

WATER QUALITY

Water Quality in Warmwater Fish Ponds. Claude

E. Boyd. 1979. Alabama Agric. Exp. Sta., Auburn

University, AL.

Water Quality Management in Pond Fish Culture.

Claude E. Boyd and Frank Lichtkoppler. 1979.

Alabama Agric. Exp. Sta., Auburn University,

AL.

NUTRITION

Nutrition and Feeding of Channel Catfish. R. R.

Stickney and R. T. Lovell, editors. 1977. Southern

Cooperative Series No. 218. Alabama Agric.

Exp. Sta., Auburn University, AL.

BREEDING

Genetics and Breeding of Channel Catfish. R. 0.

Smitherman, H. M. El-Ibiary and R. E. Reagan,

editors. 1978. Southern Cooperative Series No.

223. Alabama Agric. Exp. Sta., Auburn University,

AL.

Appendix 1

Selected References

-21-

GENERAL

Costs and Returns for Producing Catfish Fingerlings.

Robert E. Allain and W. R. Morrison.

1978. Bull. No. 831. Arkansas Agric. Exp. Sta.,

University of Arkansas, Fayetteville, AR.

Commercial Catfish Farming. Jasper S. Lee. 1981.

The Interstate Printers and Publishers, Danville,

IL.

Principles of \Varmwater Aquaculture. Robert R.

Stickey. 1979. John Wiley & Sons, Inc., New

York, NY.

Fish Farming Handbook. E. E. Brown and John

B. Gratzek. 1980. The A VI Publishing Co., Inc.,

Westport, CT.

Aquaculture; the Farming and Husbandry of

Freshwater and Marine Organisms. J. E. Bardach,

J. H. Ryther and W. 0. McLarney. 1972.

Wiley Interscience, New York, NY.

Fish Hatchery Management. Robert G. Piper, et.

al. 1982. U.S. Department of the Interior, Fish

and Wildlife Service, Washington, D.C.

Aquatic and Wetland Plants of Florida. 1978. Bureau

of Aquatic Plant Research and Control,

Florida Department of Natural Resources, Tallahassee,

FL.

Identification and Control of Weeds in Southern

Ponds. 1980. George W. Lewis and James F.

Miller. Cooperative Extension Service, The University

of Georgia, College of Agriculture,

Athens, GA.


Alabama Fish Farming Center

P.O. Box 487

Greensboro, AL 36744

( 205) 624-3651

Southeastern Cooperative Fish Disease Laboratory

Department of Fisheries and Allied Aquacultures

Auburn University, AL 36849

( 205) 826-4786

John K. Beadles, Ph.D.

Professor of Biology

Chairman, Division of Biological Sciences,

Arkansas State University, Jonesboro

State University, AR 72467

( 501) 972-3082

Dr. Roy Grizzell

Rt. 1, Box 496

Monticello, AR 71655

( 501) 367-8163

Scott Henderson, Fishery Biologist

Arkansas Game & Fish Commission

P.O. Box 178

Lonoke, AR 72086

(501) 676-7963

Andrew J. Mitchell

U.S. Fish & Wildlife Service

Fish Farming Experimental Station

P.O. Box 860

Stuttgart, AR 72160

( 501) 673-8761

Lanny R. Udey, Ph.D.

Department of Microbiology ( R138)

University of Miami School of Medicine

Fish and Shellfish Pathology Lab

(Exclusive of viral work)

P.O. Box 016960

Miami, FL 33101

( 305) 547-6563

University of Florida

J. Hillis Miller Health Center

Box J-136

Gainesville, FL 32611

( 904) 392-4777

Appendix 2

Fish Disease Diagnostic Laboratories

-22-

Jack L. Blue, D.V.M.

North Georgia Diagnostic Assistance Lab

College of Veterinary Medicine

University of Georgia

Athens, GA 30602

( 404) 542-5568

Department of Veterinary Microbiology

and Parasitology

School of Veterinary Medicine

Baton Rouge, LA 70803

( 504) 346-3306

Janice S. Hughes, Fisheries Biologist

Louisiana Wildlife and Fisheries Commission

P.O. Box 4004

Monroe, LA 71203

( 318) 343-4044

Tom Schwedler, Ph.D.

Area Extension Wildlife & Fisheries Specialist

Stoneville, MS 38776

( 601) 686-9311, Ext. 269

Thomas L. Wellborn, Jr., Ph.D., Leader

Extension Wildlife and Fisheries

P.O. Box 5405

Mississippi State, MS 39762

( 601) 325-3174

North Carolina State University

Department of Companion Animal &

Special Species Medicine

School of Veterinary Medicine

Raleigh, NC 27611

(919) 737-2910

University of Tennessee

College of Veterinary Medicine

P.O. Box 1071

Knoxville, TN 37901

( 615) 546-9230


The

-'.1Aiabama

W7Cooperative

Extension Service

AUBURN UNIVERSITY

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