|Langston University Aquaculture|
Caged Catfish Culture Problems
Marley D. Beem
EVERY YEAR MANY people across Oklahoma raise catfish in cages. Most of them do fine, but when major problems happen they are usually due to one or more of the mistakes listed below. Whether you are just starting out or are an experienced caged fish farmer, read over this list of common mistakes and you might save yourself considerable time and money.
CHECKLIST OF MAJOR CAGE CULTURE PROBLEMS
1. Wrong pond
2. Too many fish per pond
3. No marketing plan
4. Too many fish per cage
5. Poor quality fingerlings.
6. Wrong feed
7. Fish too large
8. Fish disturbed by people
9. Too few fish per cage
10. Wrong cage material
1) WRONG POND
Ponds smaller than one surface acre are generally not suit- able for cage culture. These small ponds cannot break down fish wastes quickly enough. Insufficient oxygen often kills caged fish in small ponds. I recommend that catfish be stocked loose in ponds smaller than I surface acre.
Ponds more than 1/4 covered with weeds may also have oxygen problems leading to caged fish kills. It the average depth of your pond is less than three feet it is likely to have weed problems.
Too many cattle around a pond can make the water unfit for fish. How many cattle are too many? If the pond provides good fishing, it is probably all right. Fencing your pond to keep cattle out will improve conditions for fish. Cattle can still be watered by piping water below the dam. Your local Soil Conservation Service office can provide plans for below- dam, freeze-proof stock watering tanks.
Deep ponds cannot be stocked with extra fish In fact, a pond deeper than eight feet at the end of summer may be a disadvantage. Much of the summer the six or so feet of warm water on top doesn't mix with deeper water. The colder bottom water has no oxygen and can rapidly kill fish when it mixes with the surface water in the fall. Many deep pond owners successfully raise caged fish year after year, but they should be aware of this potential problem.
Ponds must be deep enough to keep at least two feet of water under the cages. Never let your cages sit on the pond bottom or disease problems are likely to occur.
Pesticides from surrounding areas can be deadly to your fish. Let neighboring landowners around your pond know that you are growing fish and urge them to use caution in applying pesticides, especially during rainy or windy weather.
10) WRONG CAGE MATERIALS
Home-made cages are fine but do not use wire mesh from the hardware store. Galvanized wire mesh will usually rust out after only a year and fish may injure themselves against its rough surface. Use only plastic mesh or plastic coated wire mesh available from fish farm suppliers. These meshes are more expensive but will last at least six years. Sunlight will damage the plastic mesh so leave your cages in the pond year- round.
Theft is a potential problem depending on the location of your pond and must be taken into account.
2) TOO MANY FISH PER POND
Strong healthy fish can die in only one night when too many are being grown in one pond. Your fish are not safe from oxygen problems just because they are feeding well and growing. The chance of oxygen depletion or disease outbreaks
will be low if you stock no more than 1000 fingerlings per acre in the spring and harvest them in the fall when their weight approaches one lb. In general, ponds used for caged fish culture can only manage the waste from a maximum of 1000 lbs. of fish per acre. Fish wastes act as fertilizer that increases the growth of phytoplankton (microscopic plants) which can cause oxygen problems.
3) NO MARKETING PLAN
Give some thought to how you will sell your fish and do not overproduce. Local repeat customers are the best bet for small scale operations. It may take several years for you to build up your market. By starting small and growing. you will be able to learn about fish culture and the local market with much less financial risk.
4) TOO MANY FISH PER CAGE
Nine to 10 fingerlings/cubic foot of cage (300 to 350 fingerlings per 1 cubic meter cage) is the recommended stocking rate. Problems with poor growth will probably occur when more than 11 fingerlings/cubic foot (400 per cubic meter) are stocked. Build more cages instead of overcrowding the fish. Cages are cheap when you compare their cost to the amount of money spent for feed and fingerlings. Remember to stay below a total of 1000 fish per acre.
5) POOR QUALITY FINGERLINGS
The fingerlings you start out with can make all the difference in the success or failure of your cage culture operation. Look for three things when you shop for fingerlings:
Length - Five to six inch fingerlings are recommended so that your fish can reach a marketable size in one Oklahoma growing season. Spend the extra money to get this size and your investment will pay off. Ask your fingerling supplier for the length you want; do not automatically settle for whatever he has on hand.
Health - Reject fish that show signs of disease. Sure tip-offs that fish are sick include sore spots; bulging eyes; strange swimming patterns; redness around the mouth, vent or fin bases; swollen abdomen; or small white spots. In addition a healthy fish should be plump and well fleshed out. Grab one and look at it from above. If they are too skinny do not accept them. Only if pond owners look for these signs will fingerling producers be encouraged to continue producing quality fish.
Differences in size -- If some of your fingerlings are more than 112 inch smaller or larger than average, sort these out and do not stock them. The small fish will not be able to get to the feed and the larger ones will eat too much. The result is lower total growth. This thinning out of fish can be painful but do it anyway. If you have several cages you may be able to separate the different length fingerlings into different cages. Bar graders are available from fish farming suppliers to make sorting easier. Do not stock rejected fish loose in your pond; they can cause problems when they try to get to the feed inside the cages.
6) WRONG FEED
Fish in cages must get top quality feed since they cannot forage in the pond to make up for missing nutrients. Only use feeds specially made for fish. A 36% protein cage catfish feed is recommended for best results. A 32% protein catfish feed is the minimum acceptable quality.
Floating type feeds must be used, otherwise pellets will sink out of the cage before they can be eaten.
Feed pellets should not be too large for the fish to easily swallow. Fingerlings between five and six inches in length can use pellets that are one-fourth inch diameter. Four inch long fingerlings should receive three-sixteenths inch diameter pellets.
7) FISH TOO LARGE
Once catfish get larger than 1 l/4 pounds it takes more feed to get less growth out of them. Large fish are a hobby and not a way to make a profit.
8) FISH DISTURBED BY PEOPLE
It is easy to frighten your fish without even knowing it. Once this happens, feeding and growth may stop altogether for several days. Do not go fishing or shoot at turtles or snakes anywhere near your cages. Fish in cages attached to docks may have too many visitors. Do not pull up a cage to show off your fish. In winter, do not handle fish or they may have disease problems in the spring.
9) TOO FEW FISH PER CAGE
To avoid fighting always keep more than 3 fish/cubic foot of cage ( 100/cubic meter) - If you have harvested some fish but want to hold the rest, you may build a crowder wall which fits into the cage and can be slid along to concentrate the fish. Do not put catfish larger than eight inches into cages if they were not caged previously; they will fight or injure themselves against the cage wall.
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