Several species of catfish can be grown commercially. They are the channel, the blue, and the white catfishes. The channel catfish is the one most commonly used because it has the best combination of characteristics for commercial production. The number of fish to stock in a pond depends on several factors:
- The size of the pond.
- The experience of the producer.
- The length of the growing season.
- The desired market size.
The most important of these factors is the size of the pond. Fish should be stocked according to the surface area of the pond. Overestimating the area results in more fish per acre than can he safely grown. Depth plays no part in determining stocking rates.
Experienced producers can stock up to 6,000 fish per acre, to produce 6,000 pounds per acre per year. Inexperienced producers should stock no more than 3,500 fish per acre. A lower stocking density reduces the risk of losses to oxygen shortages and diseases. In time, a new producer will gain the management experience that allows higher stocking rates.
Fingerlings can be stocked at any time during the year. The best time to transport fingerlings is when the water is cool, so that stress on the fish is reduced. Fingerlings are trained to accept feed faster when temperatures begin to moderate, usually during February and March.
Before stocking, eliminate all wild fish, such as bream, minnows, and bullheads, that might eat food intended for the catfish. Wild fish can also carry diseases.
If possible, eliminate wild fish from the water supply. Saran screen with 40 meshes per centimeter can be used to filter out unwanted fish and fish eggs. Saran can be used as a sock to fit over the water supply pipe, or it can be framed into a box when large flows of water must be filtered (see Figure 5).
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Figure 5. Saran sock. |
Largemouth bass fingerlings can be stocked with the catfish at a rate of 50 per acre. Bass will eat small wild fish, preventing a rapid increase in their numbers. Bass do not tolerate low oxygen as well as catfish. If the bass are larger than 1 pound, stock catfish fingerlings that are over 8 inches long so that the bass will not eat them.
If wild fish are already in your pond, drain it completely and leave it dry for several weeks. Rotenone (5 percent wettable powder or liquid formulation) applied to remaining pockets of water at more than 3 parts per million (10 pounds per acre-foot) will eliminate any fish. In warm weather, rotenone detoxifies in 7 to 10 days. In winter, rotenone may remain toxic for more than 30 days.
Before stocking fish in a pond, adjust the water in the transport tank holding the fingerlings to match the pond water in temperature and other water quality factors such as pH, alkalinity, and hardness. This can be done by putting small quantities of water into the tank from the pond (called tempering), so that the tank water is eventually similar to that of the pond.
As a general rule, catfish can withstand a 5 degree F change in temperature without severe stress and a 10 degree F change if the water is tempered over a period of 30 minutes. For greater temperature differences, care must be taken to slowly equalize water temperatures before moving the fingerlings from the tank to the pond. In this case, adjusting water temperature 1 degree F every 10 minutes is a good rule to follow. Tempering is especially important if fish are going from cool water to warm water.
Insufficient tempering can kill the fish by temperature shock or shock from other water quality factors. If the fish are not killed by the shock, they can be weakened, which lowers their resistance to disease.
Starting with good quality, healthy fingerlings of known genetic background
is very important to profitably growing a crop of fish. Buy your fingerlings
from a producer who has a reputation for producing good fish, who knows
how to treat fish for disease, who has the equipment and the know-how to
handle them without excessive stress, and who delivers accurate counts and
weights.