Freshwater

Obtaining variation the bad way
Another way you can obtain variation is when a mutation occurs. A mutation
is a more radical change from one generation to the next and does not occur
in increments. Mutations are not very common. The main disadvantage of a
mutation is that many mutants are sterile or, if they’re fertile, they may carry
deformed genes that are not passed along to future generations. The odds of
carrying a mutation long enough to make it pure are staggeringly long, to say
the least.
Creating strains through inbreeding
The breeding process used to produce a “pure” strain of fish is known as
inbreeding. After the first brood is born and raised, pick a healthy male and
breed him back to his mother. From the next generation, select the best quality
grandson (who displays the characteristics you want) and breed him with
his grandmother. Keep repeating this process for successive generations.
This helps solidify the characteristics you want by keeping unwanted traits
from other fish out of the picture. This is perfectly normal as far as fish are
concerned, because they would breed with each other anyway, and you are
just pairing them up for the best traits.
As each new brood is born, check for males born with unique characteristics
that you want to continue on with. If the females that you started with die,
select a healthy daughter and continue on. This method of inbreeding is more
effective than line breeding, which involves mating half-brothers and sisters.
Inbreeding in mammals causes genetic defects, and many people find it a distasteful
topic generally. However, in the fish world it happens all the time.
Sometimes survival depends on it. In our opinion inbreeding in fish should
not be thought of in the same light as it is for higher animals. However, it’s
possible that no amount of evidence or argument can get you over that
hurdle. If that is the case, then inbreeding to produce new strains of fish is
not for you.
Choosing the Right Species for You
Chapter 20: Let’s Spawn!
It’s best to start out with a few of the easier-to-breed species so that you can
learn the ropes. The following examples give you basic information on a few
species that are relatively easy to breed so that you can get started on this
fascinating adventure without encountering a lot of difficult problems off
the bat.
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