Breeding of Fish
• Breeding fish is one of the steps to becoming a
skilled aquaculturist.
• Once fish are healthy enough to spawn, in order to
breed them, usually needs to be able to distinguish
between sexes and to be able to recreate natural
conditions to stimulate spawning.
• Determining the sex of a fish can be done by
observing the primary and secondary characteristics.
• In sexually dimorphic species: the sexes can be easily
distinguished by
• - Primary (shape of sex organs)
• - Secondary differences (size, shape, colour,
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• Conditioning: is feeding the fish a variety of
healthy foods to get them in top condition for
spawning
• Many fish can be conditioned using a well-
balanced formulated feed or live food such as
brine shrimp, zooplanktons etc.,
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Reproductive Strategies
There are two main categories of fish according to their
reproductive behaviours:
Egg Layers
Live Bearers
Egg Layers (Oviparous):
The majority of fish used in aquaculture purposes and
aquarium are egg-layers with external fertilization.
Egg-layers can be divided into five group:
egg-scatterers, egg-depositors, egg-burriers, nest -builders
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mouth-brooders. 4
Egg-scatters:
These species simply scatter their adhesive or non-adhesive
eggs to fall to the substrate, into plants or float to the
surface.
These species do not look after their brood and even eat
their own eggs.
These fish often schooling, fish may spawn in groups or in
pairs
Often there is large number of the small eggs laid and the fry
hatch quickly
IL:
Find examples for adhesive and non-adhesive egg scatters
from both table(food) fish and ornamental fish
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Egg- depositors:
These species deposit their eggs on a substrate (tank glass,
wood, rocks, plants).
Egg depositors usually lay less eggs than egg-scatters,
although the eggs are larger.
Egg-depositors fall into two groups: those that care for their
eggs, and those that do not (lay eggs against a surface
where eggs are abandoned, but do not eat their eggs).
Egg-depositors that care for their young can be divided into
two groups: cavity spawners and open spawners.
Cavity spawners lay their eggs in a cave, while open
spawners lay their eggs on an open surface.
These fish form pairs and have advanced brood care where
the eggs and young once are often guarded by the parents.
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Egg-burriers:
These species usually inhabit waters that dry up at some
time of the year.
The majority of egg burriers are annual spawners which lay
their eggs in mud.
The parents mature very quickly and lay their eggs before
dying when the water dries up.
The eggs remain in a dormant stage until rains stimulate
hatching.
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Nest-builders:
Nest builders build some sort of nest for their eggs and
practice brood care.
The nest is usually in the form of bubble-nest formed with
plant debris and saliva-coated bubbles (labyrinth fish,
catfish), or a excavated pit in the substrate.
Nest builders should be provided with material with which to
build their nests.
For bubble-nest builders, fine leafed and floating plants
should be provided.
The tank should have no water current to disturb the nest.
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Mouth-brooders:
Are species that carry their eggs or larvae in their mouth.
Mouth brooders can be divided into ovophiles and
larvophiles.
Ovophile or egg-loving mouth-brooders lay their eggs in a
pit, which are sucked up into the mouth of the female.
The small number of large eggs hatch in the mother’s mouth,
and the fry remain there for a period of time.
Larvophile or larvae-loving mouth-brooders lay their eggs on
a substrate and guard them until the eggs hatch.
After hatching, the either female or both parents pick up the
fry and keep them in their mouth. When fry can fed for
themselves, they are released.
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Live bearers:
Live bearers are fish that bear live young.
There are two types of live bearers:
Ovoviviparous, where the eggs form and hatch within the
female before birth
Viviparous, where no eggs are formed, and the young are
nourished through an umbilical-like cord or form secretions
by the female.
Live bearers are often prolific, easily bred species.
IL:
Find examples from both table(food) fish and ornamental fish
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Stimulation for Spawning
• One of the best ways to induce fish to spawn, especially
difficult-to-spawn species, is to stimulate natural
conditions.
• Among factors that encourage fish to spawn are the
environment, the food, and the rainy season.
Water Conditions:
• The right water conditions are among the most basic
requirements in spawning fish.
• Thus the water conditions should be similar to those in the
natural environment of the species.
• Another important environmental conditions is the right tanks
set-up including hiding places, spawning sites, lighting, water
current,
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and social conditions. 16
Food:
Without proper foods, natural conditions cannot be entirely
recreated.
Some of the live foods that often can be make a difference in
spawning success .
Stimulating the Rainy Season:
Many fish species spawn during the rainy season in nature.
By stimulating the rainy season in aquatic tanks can be induced to
spawn.
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Endocrine control of reproduction
Fish reproduction is depend on coordinated actions of
various hormones associated with the brain-
hypothalamus-pituitary and gonads under the command
of endocrine system
Hormones and compounds:
1. Gonadotropic-releasing-hormone (GnRH) contained in
the brain(hypothalamus)
2. Gonadotropin 1 & 11(GTH-1 & GTH-11)
3. Sex steroids (T , 11-KT and E2)
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Inducing Reproduction
Two methods:
1. Provide an environment similar to that in which spawning occurs
naturally
eg.
Catfish- like to spawn in enclosed space- stimulate putting some hollow logs or cans
in a pond
Goldfish- the presence of vegetation and an increase in temperature
Salmon and Trout- Changing the photoperiod in a hatchery can accelerate or delay
maturation and ovulation
2. Inject the fish with one or more naturally occurring reproductive
hormones or their synthesis
This is only effective in fish that are already in breeding condition and have mature
eggs.
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Inject the hormones for brooders
• Intra peritoneal ( IP )
• Intra muscular ( IM )
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Intraperitoneal injection
Intramuscular injection
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Select suitable
brooders
Keep in the
conditional tank
Preparing spawning
tank and hatchery
Inject the hormone
Keep the spawning
tanks
Collect the eggs
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Keep them in 23
hatchery jar
SPAWNING POND
Indian carps spawning pond
Area- 15m2
Stocking- 3-5 pairs of Brooders
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Incubation
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