What are the five types of egg-laying fish, and what are their habits?
(a) Egg-scatterers are fishes that lay their eggs in a haphazard manner on the floor of an aquarium. Some
species lay adhesive eggs that stick to the gravel on the aquarium floor or on decorations and plant
materials. Other species lay nonadhesive eggs. There is no parental care of the eggs or young; when the
eggs are laid, they are forgotten. In many cases, steps must be taken to prevent the parents from eating the
eggs and the newly hatched fry.
(b) Egg-buriers are fish that lay their eggs in the mud of rivers and ponds. The adults lay their eggs in the
mud and die when the rivers and ponds dry up. The eggs survive in the mud, and when the next rains
come, the young hatch. In aquariums, they lay their eggs in the material on the floor of the aquarium.
(c) Egg-depositors have complex spawning routines and are excellent parents; these fish will usually select
their own mates. They clean off a nesting site where the female deposits her eggs, and the male fertilizes
them. The parents usually take turns guarding the nest; they constantly fan the nest and eggs with their
fins to keep them clean from dirt or silt and dust that may settle on them. When the young fry hatch, the
parents will keep watch for several days to protect them from predators.
(d) Mouth-brooders are fish that carry their eggs in their mouths until they hatch, after which the young may
continue to be carried in the parent's mouth until they are ready to fend for themselves. In some species,
the young, after leaving the parent's mouth, may return if threatened. After the eggs deposited by the
female are fertilized by the male, the female, and in some species the male, will go around the pick up the
eggs by mouth. During this incubation period of two to three weeks, the parent does not eat.
(e) The nest-builders construct nests in which the eggs are deposited; it is usually constructed by the male.
This nest may be a bubble nest on the surface made from saliva-blown bubbles or may be prepared from
materials found on the floor of the aquarium. After the eggs are fertilized, the female should be removed
because the male will become aggressive toward her; the male then guards the nest.
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