Page 64 - Encyclopedia of Aquarium and Pond Fish, 3rd Edition

62 FRESHWATER FISH: BREEDING

during which time the adult fish does not feed. The fry emerge
from their parent’s mouth when they are able to swim freely.
Mouth-brooding is best documented in members of the cichlid
family, but it also occurs in some bettas and catfish. These fish
produce far fewer eggs than other egg-layers, but their eggs
stand a better chance of survival.
Survival of the fry
Fry that hatch in the open initially lie largely immobile, close
to where they hatched, until they have digested the remains
of their yolk sac—a process that may last several days. Many
species that guard their eggs also show parental care toward
their fry. Some cichlids, for example, herd their offspring
into spawning pits that they excavate in the substrate,
where they can keep watch over the brood. Several such
spawning pits may be dug and used during the early days
Heavily pregnant
female is less agile after the young have hatched. The combined tail movements
when swimming
of the fry set up tiny currents above the pit, increasing the
Abdomen flow of oxygen-rich water over the developing young. Even
The bulging body of this Platy is a clear sign that becomes
she is in breeding condition. When a female swells with swollen when the fry are free-swimming, the adults will chase after
eggs or developing young, she is said to be “gravid.” and catch individuals that separate from the school and carry

EGG-LAYING BEHAVIORS
Fish display a wide range of egg-laying behavior, anabantoids inhabit calm waters and build bubble
reflecting the way in which they have adapted to a nests for their eggs. Some anabantoids, however, have
variety of environments. Even related species may have changed to mouth-brooding in order to exploit more
very different egg-laying habits. For example, many turbulent waters that would destroy bubble nests.

BEHAVIOR DESCRIPTION TYPICAL EXAMPLES
Egg-scattering The female releases a large number of eggs at random, some of Egg-scatterers include cyprinids,
which stick to plant leaves, while others become lodged in the such as barbs, danios, and
substrate. The fish become increasingly active prior to spawning, rasboras, as well as tetras
with the males pursuing the females vigorously. The fish show no and many other characoids.
parental care and may eat their own eggs and any fry that hatch.
Egg-depositing Egg-depositors often form pair bonds. A pair will carefully choose a Discus, angelfish, and various other
safe, clean spawning site where they can lay their eggs. This may be cichlids. A number of catfish, such
a rock, the underside of a leaf, or even a cave. After spawning, the as bristlenoses and loricariids, also
fish stay in the vicinity of their chosen site, driving off other fish reproduce in this way.
that come too close to the eggs. They also jealously guard their fry.
Egg-burying This behavior is shown by species dwelling in muddy pools that dry Annual killifish, such as the
up each year. After the water has evaporated, the eggs lie dormant nothobranch group, and
in the dried mud and hatch when the rains return. The fish must Argentine Pearl Fish.
develop rapidly and spawn again before the dry season begins.
Mouth-brooding One of the parent fish takes the eggs into its mouth and retains Various cichlids, including many
them there until they hatch. This behavior keeps the eggs out of African Rift Valley species, as
sight of predators in open habitats and also helps to prevent them well as anabantoids that occur in
from being swept away by strong currents. fast-flowing water, and some catfish.
The best-known bubble nester is
Bubble-nesting The nest is made of mucus bubbles blown at the surface by the male Some anabantoids, including the Siamese Fighting Fish. The eggs
and may be anchored to plants. It holds the eggs, and later the fry, Siamese Fighting Fish and Pearl hatch about 48 hours after being
together in one place where they can be closely guarded. The male Gouramis. Hoplos catfish also laid. The male guards the fry until
often drives the female away after spawning and keeps watch alone. exhibit bubble-nesting behavior. they are free-swimming.

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