Page 71 - Encyclopedia of Aquarium and Pond Fish, 3rd Edition

BREEDING IN AQUARIUMS 69

Many freshwater
species are now bred
GROWTH AND DEVELOPMENT OF A PLATY commercially for the
aquarium trade. This
Young livebearers, such as platies, are free-swimming at birth and have breeding farm is in
a remarkably consistent growth rate, averaging up to ⁄100 in (0.3 mm) Singapore, where the
1
per day. Initially, both sexes develop at the same pace, but the females climate allows fry to be
have a growth spurt after maturity and eventually outgrow the males. reared in outdoor ponds.
The fish eat naturally
occurring foods plus
Three weeks after dietary supplements.
birth, traces of color
are starting to show on
this young fish, but it is
still quite inconspicuous Problems and solutions
in the tank. It is now Difficulties can crop up at any stage during the breeding cycle,
large enough to be safe
from being eaten by the starting with the failure of the fish to spawn at all. It may be
other tank occupants. that you do not have a pair, or that the fish are not yet mature
enough to breed. If the fish spawn but the eggs prove to be
At five weeks old, the infertile, the male of the pair could either be too old or, if he
coloration of the fish is is a livebearer, have a damaged gonopodium. Swap the males
becoming clearer. The of different pairs around to see if this has any effect. With egg-
fins are proportionately
larger and more layers such as barbs, add an extra male to the spawning tank to
elaborate. The body is increase the likelihood of success. If eggs are attacked by
less streamlined, with fungus, you can treat the water with a little methylene blue
a more angular back
and a bulkier abdomen. to control the problem, although the presence of fungus may
also be an indication that the water temperature is too low.
By nine weeks of age, If the young fail to thrive, or even die off, reexamine their
the patterning and feeding regimen. Study the abdomens of fry with a hand lens;
richness of coloration their bodies should be transparent enough to see if there is food
are fully apparent. Now in the gut. If there is not, the food you are giving the fry may
sexually mature, the fish
can be identified as a be too large for them to eat. The fry may also perish if the
male by its gon opodium, water quality deteriorates, so monitor this closely during the
which is just visible rearing period. There will inevitably be a few deformed fry
behind the pelvic fin.
in any brood, and these should be humanely culled.
When the fry become sufficiently mature, they can gradually be switched
to their adult diet. Make sure that you provide enough to meet their rapid
water is too cold when their anabantoid organs start to growth rate, while taking care not to overfeed them.
function at about three weeks of age, the fry could become
fatally chilled when they try to breathe at the surface.
With territorial species, separate young males before they
start to become aggressive toward the rest of the brood. Male
Siamese Fighting Fish (see pp.104–106), for example, must be
kept apart by the time they are three months old. Young
livebearers should also be separated as soon as you can sex
them, to prevent littermates from interbreeding. A female
livebearer can store sperm in her body throughout her life, so
any unplanned matings like this will endanger your breeding
program, since you will not know for sure which male sired
the fry. Avoid housing together the young of related species, such
as swordtails (see pp.160–161) and platies (see pp.162–164), which
will readily crossbreed, or hybridize. It is difficult to predict the
appearance of hybrids, and they tend to be less attractive and less
fertile than the species from which they originate.

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