Freshwater

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Part IV: Breeding and Other Fun Stuff
Picking new stock
When selecting future breeding stock from your own bred stock and new purchases,
choose the most colorful, vigorous fish in the group and move all the
females to one tank and the males to another tank. You don’t want to rely
upon chance sexual encounters or you may never be able to develop the
strain you’re seeking.
Understanding Genetics
A while back, a bored young monk named Gregor Mendel did a few experiments
with peas in a quiet monastery garden. He selectively bred pea plants
for certain characteristics and kept track of those characteristics. He was
surprised to see traits (physical signs) not seen in either parent plant appear
in their offspring. Everyone thought he was weird, but he learned a lot of cool
stuff — such as, what you see is not necessarily what you get (he had discovered
recessive genes). Selective breeding allows you to choose fish that have
the characteristics you’re searching for and breed them until that characteristic
remains stable from generation to generation. And, like Mendel, you may
end up with a few surprises to boot.
Choosing the best
To breed selectively, you need to choose a male that possesses characteristics
you want to develop into a pure strain, so that generation after generation
of fish display the same certain colors, fin types, and whatever other
factors you isolate. Selecting a good female may be a little more difficult,
because they usually do not carry as much color as the males. Just try to
pick a full-bodied female in good health.
Obtaining variation the good way
Few strains (an entire breeding family tree) produce identical fish from generation
to generation. If they do, it can take a very long time to develop fish
that are identical in color and shape consistently by interbreeding them with
each other . Because genetics are so varied, it is possible that you may end
up with a brand new characteristic (not seen in the parents) within a few
years. This occurs because of recessive genes (genes that are present but
which are not “turned on” and thus don’t show their traits in the physical
makeup) which make an appearance periodically.