transportion of catfish in Nigeria

TRANSPORTING CHANNEL CATFISH
FRY AND FINGERLINGS IN PLASTI C
BAGS World Aquaculture, Fish size ranges from 4- to
10-inch fingerlings to 1- to 3-lb
food-fish. Hauling large numbers
of fish of these sizes usually requires considerable amounts of
water and a big truck. How ever,
shipping fry and 1- to 2-in ch
fingerlings can be accomplished
effectively in a van or small truck
using plastic bags, styrofoam ice chests and pure oxygen gas. Large plastic bags (18 X 32 inches)
are commonly used for fish
transport. Four cornered bags are
preferred to avoid corner collapse
which can suffocate large numbers
of fry that become trapped when pockets form. Bag thickness should
be 4 mil to help minimize
punctures. Bags are usually
doubled to ensure that they
remain air tight if one should leak. The plastic bags are filled with
water, fish and oxygen gas.
Typically, each bag is filled such
that 1/4 of the volume is water (2
gallons is common) and 3/4 will be
oxygen. Water and fish are added. The remaining air is removed by
hand, compressing or squeezing it
from the bag. The bag is
completely refilled with pure
oxygen gas. Oxygen is added
through a flexible tube attached to a small compressed gas cylinder.
The neck of the bag is twisted and
then sealed tightly with one or
more large rubber bands. The
number of fish placed in each bag
is determined by fish size and weight, and estimated travel time
(Table 1). Table 1. Pounds per gallon of fish
that can be transported in bags for
several shipping times. Fish size Travel time (hours) 1 12 24 48 Eggs 0.5-1.5 0.5-1.2 0.5-1.0 0.2-0.5 Yolk-sac
fry 1.0-3.0 0.7-2.5 0.4-2.0 0.1-1.0 Swim-up
fry 0.5-2.0 0.4-1.6 0.4-1.2 0.2-0.6 1- to 2- inch
fingerlings 1.0-3.7 0.9-3.2 0.7-2.7 0.3-1.3 Adapted from Dupree and Huner (1984) -- Third Report to the Fish Farmers, US Fish and Wildlife Service. At a water temperature of 65o F. The data in Table 1 were presented
by Dupree and Huner in 1984, and
are for a variety of fish species.
The fin spines of 4- to 10-inch
catfish fingerlings readily puncture
bags and make transport by this method risky. A reasonable but
conservative loading rate (24-hour
transport) for channel catfish fry is
1/2 lb of fry to each gallon of
bagged water (Table 1). There are
approximately 10,000 catfish fry to the pound. Two gallons of water
would be required to ship 10,000
channel catfish fry on a 24-hour
trip (1/2 lb fry/gal X 2 gal X 10,000
fry/lb). The presence of organic
substances in shipping water -- material released by hatching eggs
or feces from fish fed, less than 12
hours, before transport -- reduces
the load capacity. Ice can be added
to an insulated shipping container
(ice chest) to help keep water temperature close to 65o F. Ice
should not be used with tropical
fish or tilapia. Shipping water should have
several desirable chemical
characteristics: pH, 7-8; carbonate
alkalinity, 100-150 mg/l; and
calcium hardness, 125-250 mg/l.
Because the bags are sealed, respiratory carbon dioxide
accumulates in the water and
lowers pH. Bicarbonate alkalinity
helps to prevent pH from
dropping. Sodium bicarbonate
(baking soda, 1/8 to 1/4 tsp/gal) will increase bicarbonate alkalinity
and pH. Food grade calcium sulfate
(gypsum, 1/4 to 4/10 tsp/gal) will
en hance calcium hardness. Adding
0.2 to 0.5% sodium chloride (table
salt, 1-1/4 to 3 tsp/gal) is recommended. Once fish have arrived at their
destination, they should be
tempered to their new
environment as soon as possible.
Float the bags in the new water
(pond or tank) for 30 minutes to allow bag temperature to
equilibrate with environmental
temperature. Resist the
temptation to open the bag and
aerate it with a bait agitator or air
stone. The build up of carbon dioxide during transport lowers
the pH of bag water. Aeration will
rapidly remove carbon dioxide and
simultaneously increase pH. A
sudden change in pH can shock and
kill the fish. After the 30 minute acclimation period, open the bag
and gradually mix the bag water
with new water; then release the
fish. For more information call us on 08032861326.

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