Feeders
Catfish may be fed by hand from the bank or boat, or by using some type of mechanical feeder. Hand feeding more than 10 acres of intensively cultured catfish ponds is too time consuming and laborious, thus some type of mechanical feeder should be used on larger farms.
Feeding Rates
Several factors affect the amount of feed a catfish will eat, such as:
- water temperature
- water quality
- size of the feed
- palatability or taste of the feed
- frequency of feeding
- the way fish are fed
- location of feeding sites
- type of pellet used (floating or sinking)
- health of the fish
- size of the fish
Feeding Practices
Manner and time of feeding, as well as the amount and type of feed, can have a profound effect on the growth and size variation and the quality of the catfish produced. A large variation in the size of catfish produced usually is the result of underfeeding (feeding the fish less than they should have) or feeding in a small area of the pond. In underfeeding, the larger, more aggressive catfish eat a larger share of the feed and become bigger at the expense of the smaller catfish.
This also happens when feed is offered in only a small area of the pond since the larger, more aggressive catfish quickly learn where the feed will be put in the pond and are there waiting for it. Thus, to produce catfish uniform in size, and to maximize profits, it is equally important that catfish are fed the proper amount of feed daily and the food is distributed as evenly over the pond as possible.
Feeding twice daily, if possible, will usually improve feed consumption and feed conversion. This means that one-half of the daily allowance is fed in the early morning, and the other half later in the day. If the catfish are fed only once a day, morning is the preferred time since feeding in the late afternoon increases the amount of fat deposited, and this can affect the quality of the processed fish.
Feed should not be offered until the oxygen level of the pond water is at least 4 parts per million (ppm) or higher because feed consumption goes down dramatically at lower oxygen concentrations. Oxygen requirements for catfish increase greatly during feeding, so it is best not to feed in the early evening when oxygen concentrations in the water are decreasing.
Record Keeping
You must be able to closely estimate the number of fish and the weight of fish in every pond at any given time if you want to be successful at raising fish. If the weight of fish in a pond is underestimated, not enough food will be fed, resulting in poor growth, poor feed conversions, and increased time required to get the fish to harvestable size. If the weight of fish in a pond is overestimated, the result will be overfeeding, poor feed conversions, and very likely, severe water quality problems.
Water Quality
Maintaining good water quality in production ponds is absolutely essential. Failure to do so will result, at best, in poor growth and high feed conversions or, at worst, a total loss of all fish in the pond. Remember that the fish in the pond are living in their own wastes. Thus, the weight of fish that can be produced in a pond is limited by the ability of that pond to provide adequate oxygen, (not only to keep the fish alive but to enable them to metabolize their food and grow) and to break down nitrogenous wastes.
Harvesting
Different methods can be used successfully to harvest fish. The method used depends on the production system, type of pond and harvest strategy. Fish can be harvest by fishing, trapping or seining.
The only way to harvest all fish from a pond is by draining. When complete harvesting is desired, fish are removed by seining and the few remaining fish are harvested by dipnetting. Harvesting the last remaining fish (scraping out) from a pond is time consuming, especially if many pot holes or low areas exist in the pond basin. Draining ponds and refilling means lost feeding days and a fuel bill if pumping is required.
On commercial farms, seining is the most efficient method to harvest a predictable large volume of fish with one effort. For hill or watershed ponds with deeper water, and irregular bottoms and banks, partial harvesting can be done by trap-seining using various techniques. Trapping fish with a seine is best accomplished when fish are feeding well and ponds are several acres and larger. Fish can become wary of this method and difficult to catch unless it is used infrequently (only once every week or longer).
In small ponds, large lift nets with centrally located feeding rings have been somewhat successful when used infrequently. Many producers use a seine to harvest only the market-sized fish from levee ponds that have graded bottoms. This method is often referred to as topping and became popular in the 1970?s. A seine with a selected mesh size is used along with other grading devices to capture fish of a desired minimum size; smaller fish remain in the pond.
Transporting
Catfish, like other livestock, are sensitive to changes that occur when they are handled. Transportation stresses fish due to crowding, changing temperature conditions, and general over excitement from handling. Fish may become spined or water quality conditions can quickly deteriorate. Fish have to be in good condition and healthy before they are transported. Sick or weak fish will probably die, or a disease problem will worsen. Fish not handled properly may develop a disease or die one to seven days after they are transported.
The following steps should be taken to prepare fish for hauling. Do not feed fish for at least two to three days in the summer and four to five days in the winter before they are transported. Fish with full stomachs handle poorly, and any regurgitated food or expelled fecal matter fouls the hauling water.
Fish should be hauled at cool water temperatures to lower their metabolic rate, calm them and lower their oxygen consumption. In summer, fish should be hauled in water 16º to 18ºC.
Transport fish in good quality well or spring water if possible, rather than pond water, unless the water is cool and clear, or if only a short trip is required from pond to pond. Pond water with an algae bloom should be avoided unless absolutely necessary and the trip is short.
Handle fish during the coolest time of the day, and avoid time out of water, especially when it is hot or windy. Do not overload dip nets and loading baskets, and try to move fish in a cushion of water.
source: www.ksuaquaculture.org
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