FINGERLINGS TRANFER AND EGG MANAGEMENT IN BREEDING

Transferring fry This method is the same as above
except the spawning containers are
checked every three days. Males
are allowed to incubate the eggs.
Once hatched, the fry are poured
from the spawning container into a bucket and transferred to a
nursery pond. Transferring eggs Spawning containers are checked
every two to four days. When
found, eggs are transported to the
hatchery. Hatchery Management Hatching catfish eggs in a hatchery
is the most efficient method of
producing fry and fingerlings. Eggs
can be incubated in troughs made
of wood, fiberglass or metal. They
are usually about 8 feet long, 18 to 24 inches wide and about 12 inches
deep. Paddles or aerators gently
circulate water in and around the
egg masses to provide sufficient
oxygenation. Egg masses are
placed in ¼-inch hardware cloth baskets that are suspended in the
hatching trough. Troughs are designed so water
enters one end at about 5 gpm and
drains through a stand pipe at the
other end. The water must be 75°F
to 85°F for successful hatching.
Oxygen concentration of the water should be at least 6 parts per
million (ppm). Water pH should be
between 6.5 and 8.0. Egg masses are subject to bacterial
diseases and fungal infections.
Frequent disinfection of equipment
and troughs and a clean water
supply minimize these problems.
Removing infertile eggs and debris will help avoid fungal infections. At hatching, sac fry fall through the
wire basket and usually school on
the bottom of the tank. Sac fry
receive nourishment from their
yolk sacs. In about three days, the
yolk sac is absorbed, and the fry turn black and begin swimming to
the surface in search of food. Swim-
up fry begin feeding at this stage.
Sac fry can be left in the hatchery
trough or siphoned to a nursery
tank. Troughs or tanks must be cleaned several times per day to
prevent water quality
deterioration. Once fry are feeding, transfer them
to a nursery pond. Numbers of fry
stocked into a pond should be
estimated by volume or weight.
Stocking density depends on the
size of fingerlings desired at harvest. For example, stocking
10,000 fry per acre will yield 7- to
10-inch fingerlings in about 150
days. Stocking 100,000 fry per acre
will yield 3- to 5-inch fingerlings in
about 150 days. Feed fry and fingerlings frequently.
As the fingerlings grow, they will
eat less food in proportion to their
body weight. Harvesting and Transport Fingerlings are harvested more
easily from ponds with clean, flat
bottoms and no weeds. Fish can be
partially graded with the harvest
seine. For example, a ½-inch seine
will retain fingerlings 6 inches in length or larger. Fingerlings can be
graded further using grading
boxes. Grading boxes can be made
with aluminum or stainless steel
rods. Rods are spaced to allow
certain size fish to pass through them. Most grading is done in
tanks or vats. Properly designed and equipped
fish transport tanks and trucks can
haul fingerlings long distances.
Hauling tanks should have electric
aerators. Bottled oxygen or air
blowers are needed with heavy loads of fish. Bottled oxygen is a
good back-up to electric aerators.

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