Methods of reproducing.
Fish which breed in this way either spawn in pairs or in groups. Males
and females release milt and eggs into the water at the same time.
These are mixed together and the eggs are fertilized. The fertilized
eggs float away in the current or sink to the bottom, where they lie
with the substrate. There is no parental care given, so large amounts
of eggs are produced. The Characins and Cyprinids are two of the species
that lay their eggs this way.
Many fish species build nest in one form or another, whether it is
a simple pit dug into the gravel or the elaborate bubble nest. No
special breeding setup is needed, when ready to spawn the fish construct
a nest by blowing bubbles, often using vegetation to anchor the nest.
The male will keep the nest intact and keep a close eye on the eggs.
The female should be removed after spawning. Care is needed to raise
the fry and the tank should have a glass cover to help keep the nest
moist and warm. The Gouramis, Anabantids and some catfish are the
most common of this type of spawners.
In this case, the eggs are either laid on a flat surface, like a stone
or plant leaf or even individually placed among fine leafed plants
like Java moss. The parents usually form pairs and guard the eggs
and fry from all danger. The Cichlids are the best known species for
this. Some Catfish and Rainbowfish are also Egg depositors. The setup
for these fish will vary with the species, but usually you have to
provide a flat stone, broadleaf plant, cave or a broken flower pot.
Sometimes you can remove the item that the eggs have been laid on
to a separate hatching tank.
The females usually lay their eggs on a flat surface where they are
then fertilized by the male. After fertilization the female picks
up the eggs and incubates them in her mouth. Even after hatching the
fry will return to the safety of their mothers mouth if danger is
near. Brood numbers are usually small, since by the time the fry are
released they are well formed and loses are minimal. The best known
Mouthbreeders are the African lake Cichlids.
The annual Killifish are known for this method of reproduction. As
the pools where they live dry out, the fish spawn. Pressing their
eggs into the substrate. The pools dry out completely and the adults
die, but the eggs remain in the dried mud. When the rains return and
the pool refills the eggs hatch and the cycle is repeated. Killifish
eggs can stay viable for many years in the dried out mud.
The livebearers do not lay eggs at all, they are fertilized internally
and carried to term inside the mothers body. The broods are small
and the fry are well developed when born. The Guppy swordtail and
Platy are the best known members of this group.