African catfish performs optimally in temperature above 25 degree Celsius. This does not mean temperature below 25 degree Celsius will kill your fish. It will only reduce the growth potential of your stock.
Catfish cultured in a deep earthen pond of depth between 3 to 6 feet can easily adjust to temperature by swimming to the warmer or cooler depth. However, studies have shown that shallow ponds are more affected by change in temperature (cold or hot temperature). Whether in earthen ponds or other types of ponds, cold weather affects the performance of African catfish and its environment in different ways as explained in this article.
- Reduced survival rate especially in small fishes and sometimes in bigger ones. As a matter of fact, stocking fingerlings or fry in an open pond (earthen pond) during cold season is not a welcome idea. It is better you allow your fishes to grow up to around 12 grams in hatchery before you stock them for better survival rate. Bear in mind that mortality increases beyond normal in this period.
- Feed consumption reduces, or sometimes catfish refuse to eat because of slow rate of metabolic activities. A carefree farmer might make a wrong decision by overfeeding catfishes that are not willing to eat.
- Slow growth in catfish is more pronounced in cold weather conditions especially when it lasts longer than their first thirty days in grow-out ponds. The slow growth in catfish during this period is traceable to poor feed consumption, ineffective digestive system among others.
- It takes more weeks for fishes to attain normal size per period of time. For instance, it takes between 23-25 weeks for juvenile stocked in my farm to attain an average size 2kg. However, fishes stocked in Harmattan season might take up to 27 weeks to attain same size.
- Profit margin reduces significantly because catfish market in Nigeria favors producers of big fishes more than their counterparts that produce small sized fishes. It takes special formulated feeds that cost about 20 percent more to achieve a normal growth rate.
- Low intensity of sunshine at this period discourages growth of water plants in the ponds, leading to change in pond water color. At this period, it is not uncommon to see pond water turning to brown, grey or black. No water plant to extract ammonia in the pond.
- Ammonia build-up in pond makes pond water to have odor. The ammonia is built up fast in the pond due to possible overfeeding during this period of time.
How to enhance favorable microclimatic conditions and better performance in cold weather
- Increase stocking density to compensate for loss due to mortality, and to generate heat from high density of fish population. Surviving fishes can later be shared into other ponds when temperature improves.
- Fishes in open tanks can be covered or shielded from direct effect of Harmattan or cold weather with the use of tarpaulin.
- Regulation of temperature for indoor tanks with the use of heaters where applicable or burning of charcoal to generate heat.
- Feeding should be done when atmosphere is warmer to enhance response and reduce waste.
- Reduce feeding quantity to avoid waste. Feed should be given based on response and not what they should eat.
- Reduce feeding frequency.
- Increase the quality of self formulated feeds by improving the energy and protein level of your feed. The little they eat will provide them with necessary nutrients.
- Add few weeks to your normal season. Do not determine your fish maturity with length of days but quantity and quality of feed consumed.
- Boost your stock’s immune system with vitamins and antibiotics specially formulated for catfish to improve their response to feeding. This will also allow them to adjust and adapt to changed weather.