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Catfish Farming

Catfish farming in the United States has experienced tremendous growth in the past twenty years. Production has increased from 5 million lbs in 1972 to nearly 500 million lbs in 1992. The majority of production is concentrated in the Mississippi Delta region with an estimated 125,000 acres of ponds. Channel catfish is the most widely cultured catfish species. Catfish farms in Florida differ greatly from the large, established operations in the leading catfish producing states. Approximately 95% of Florida catfish producers have less than 20 acres of ponds and view aquaculture as an alternate means of supplementing their income.

Catfish production is capital intensive and involves many risks and has been described as one of the most management intensive forms of farming. In addition to the high entry cost, Florida producers are faced with the many growing pains of a young industry. Among these are higher production costs associated with a small scale of operation and limited developed infrastructure. Additionally, market conditions are influenced by large producers and processors which pose new challenges for small producers in finding their market niche.

Proactive Pond Management

In the southern U.S., many catfish farms are managed to maximize production with high stocking (5 - 10 thousand/acre) and feeding (75 - 150 pounds/acre/day) rates. Typically, seasonal feeding rates are increased on these farms until mechanical aeration is necessary. Often, therapeutants are required to manage the disease and parasite problems which accompany or follow these poor water quality periods.

Important steps for implementing proactive management follow.

Waste products from catfish which are efficiently converting feed to tissue will enrich the pond with nutrients, resulting in plankton blooms. Food conversion efficiency in catfish goes down when they eat more than necessary for optimal growth. When the catfish are overfed, these additional waste products stimulate the development of large, unmanageable plankton populations. Nutrient and/or oxygen requirements of one or more of the populations may exceed the supply rate, resulting in a crash. Nutrient concentrations may reach toxic levels before these populations can recover. Aeration and therapeutants may be required to limit the onset of fish disease or mortality.

It is very unlikely that all your ponds can be fed at the same maximum rate. The most reliable way to determine your maximum feeding rate is to monitor water quality for each pond. Daily dissolved oxygen (DO) and temperature, and regular (weekly or bi-weekly) alkalinity, pH, total ammonia nitrogen (TAN), and nitrite-nitrogen measurements are critical to develop a production profile for each pond. This water chemistry profile coupled with daily and extended weather forecasts can help you avoid or lessen the effects of critical water quality problems, and, improve profit potential through increased feed conversion efficiency and reduced aeration expenses. Water quality test kits, which can perform these tests for fish farmers, cost approximately $175 - $200. Time requirements for daily DO measurements will average 10 - 15 minutes/pond/day.

Organic debris accumulates on pond bottoms as a result of any catfish production. Drying and stirring this debris helps to oxidize organic wastes and may help curtail chronic disease problems. Seining efficiency should improve also when the pond bottom is reflattened. Make sure to repack the pond bottom before refilling.

Wastewater guidelines prohibit discharge of pond bottom sludge to streams. Pond bottom sludge may be applied to fields or gardens as long as it cannot contaminate streams.

After cleaning, adding ag lime can improve the production potential of most ponds by increasing their buffering capacity. In ponds with total alkalinity of 60 mg/l or less, 1 - 2 tons per acre are recommended. For ponds with total alkalinity of 60 - 100 mg/l, 1 ton per acre is sufficient. If a pond leaks badly, liming isn't cost effective. As you record and maintain information on your ponds, you can determine the quantity and frequency of liming required for each pond. Ag lime may be purchased from most agri-chemical dealers or from highway construction companies.

What to Observe

Average early morning (6 - 8 A.M.) DO concentrations will decline slowly through the spring to summer period, even though the day to day concentrations may fluctuate. During this period, morning pond temperatures and your feeding rate will slowly increase. Once pond temperatures begin to stabilize, trends in DO concentrations become very important. When morning DO decreases consistently for 3 - 5 days (3.0, 2.3, 1.8 mg/l, for example) consider this a significant trend and reduce feed input. When the morning DO concentration returns to pre-decline levels, increase feed input by 10%/day to original levels. Skip feeding on days when morning DO is less than 1.8 mg/l.

A rapid increase in morning DO concentrations, when weather conditions are stable, indicates that an algal bloom has begun. Increasing feed inputs during these periods will usually result in a serious water quality event if the bloom crashes.

A weather forecast predicting cloudy (overcast), cool or stormy weather can be expected to result in declining DO in many ponds, especially those with dense algal blooms. Reducing feeding rates as a weather front approaches can soften the impact on DO, and, nutrient concentrations and plankton populations. Despite the reduced feed inputs, plankton populations can still crash if you push the pond limits during poor weather conditions. Your ponds should recover within a day or two if you have not been overfeeding. Be sure to measure DO and TAN frequently during these difficult periods. Keep a record of these measurements for future reference.

Proactive pond management helps to prevent reliance on mechanical aerators. If your pond develops a DO problem, use your aerator. As soon as weather or pond conditions improve, stop aerating and allow the pond to recover normally.

Abrupt changes in pH and alkalinity usually indicate major changes have, or, are occurring in the pond phytoplankton (algae) populations. As algal population carbon requirements exceed available carbon dioxide levels, algae will use carbon from the pond buffer supply and alkalinity will decline. Reduce feeding for a few days to allow algal populations and alkalinity time to stabilize. Heavy rains can also cause alkalinity to decline. In either case, alkalinity should stabilize at or near previous levels; if not, add ag lime as needed.

As feeding rates and pond temperatures increase, TAN and nitrite-nitrogen levels will increase. When you reach the target feeding rate (25 - 40 pounds/acre/day), TAN and nitrite-nitrogen levels should stabilize near 0.4 - 1.0 mg/l and 0.002 - 0.3 mg/l, respectively. However, ponds which are highly enriched from years of accelerated production may have nutrient levels outside, usually above, these ranges. At this point, changes in nutrient concentration indicate changes in algal or bacterial populations if weather conditions are stable. Algae use ammonia readily when sunlight is available. If feed rates are constant, an increase in TAN concentration usually means that algal populations are declining. Weather changes that affect DO concentration, will affect TAN concentration also, because algae are the primary DO contributors/users and TAN users.

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This page was last updated on November 15, 2002