0 - WorldFish Center

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005-Lun 25;Jun 15;Jul 04;Aug 24;Aug 13-'Sep 03kt 2310ct 12-l$yO
Sampling date
Fig. 3. Growth of handsexed Oreochromlr nllotkus males in the 0.0077-ha farm pond of
Ibrahim Ansah (Mampong-Nkwanta, Ghana) receiving chicken and goat manure, and farm
residues.
The decline in fish growth in the zero
input experiment was expected. The low
nutrient levels did not encourage growth
of algal and other foods which are essen-
tial to maintain and promote growth af-
ter any initially available food resource in
the water was used up. The fish lost weight;
most of them died and this affected over-
all pond production.
The situation was different in ponds with
previous fertilization histories. Production
was higher in the recently used pond than
in the "fallow" pond. This could be attrib-
uted to the leaching of nutrients from the
pond as a result of the long period of ex-
posure to weather elements like rainfall.
Production in the recently used pond,
-0- We~ght +Total length
220
- 200
- 180
-160
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-100 -
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- 40
- 20
however, did not indicate another good
yield if the pond was cropped another time.
Obviously, the overall growth attained
in the manured experiments was low. This
was attributable to human error in the
manuring schedule which resulted in a lower
quantity of manure being applied. How-
ever, the overall response of fish growth
to the different manure conforms to ob-
servations in the literature (Hopkins and
Cruz 1982; Pullin and Lowe-McConnell
1982; Owusu-Frimpong et al. 1990, 1991,
1 992).
Fish growth in the pond receiving farm
and household wastes and residues was
highest. It can be inferred that fish production
can be increased fivefold with on-farm and
household wastes as inputs.