Feed Quality

The quality of feed refers to the nutritional as well as the physical characteristics of the feed that allow it to be consumed and digested by the fish. The feed should contain all the nutrients required by the fish, in the right proportions for good performance (growth and health). The specific nutrient requirements for fish vary with the fish’s size and reproductive state.

Below presents the nutritional requirements of catfish. The nutrients within the feed should also be easily accessible to the fish and be digestible. The physical attributes of the feed determine the degree to which the feed affects water quality and consumption rates by the fish.

The physical attributes of a good feed, therefore, are:

1. The ingredients used in the feed should be finely ground. The pellets will have uniform colour and you should not be able to distinguish morsels of maize for example.
2. The feed must be without fines or dust. If too many fines are in the feed, too much will be wasted in the form of a powder that floats on the water surface. Tilapia may eventually consume this powder but larger catfish will not.
3. The pellet should be firm with a water stability of at least 30 minutes. The pellet’s water stability refers to the time it takes for the pellet to completely fall apart in water. Proper cooking assures that the starches have gelatinized and this helps hold the pellet together.
4. The pellets should be of uniform size and of correct size so the fish can swallow them. A size of about ¼ the gape of the mouth is advised.
5. The feed should be palatable to the fish with a good taste, smell and feel. Fish will spit out or only slowly consume feed that is not palatable.

One of the major differences between feeding fish and feeding terrestrial animals is that once fish have been fed, the excess feed cannot be retrieved from the water in pond, unless an extruded floating pellet is used, and even this is impractical. Land animals are fed from containers and excess feed can be retrieved, but even land animals have problems when there are too many fines in the feed. The fish in this case will be unable to eat all the feed and obtain all the nutrients it needs for growth as the feed will have disintegrated before they can consume it. This results in poor growth performance and a higher risk of poor water quality. Therefore, the higher the quality of feed that is used, the less wasted feed and the easier it is to manage pond water quality. With better water quality, the greater the pond’s potential carrying capacity. Catfish do much better when the starches in the feed are adequately cooked, which is more likely to happen with extruded feeds, as opposed to pelleted feeds. However, some pellet mills will cook the ingredients. A farmer can tell by checking the integrity of the pellets. If the pellets of feed can float, it usually means that the ingredients have been cooked. Floating feed provides an added advantage in that the farmer not only knows when the fish have started feeding, but the farmer will know when the fish have stopped feeding. Even though catfish are thought to feed on the pond’s bottom, they are easily trained to feed wherever the food is, even at the surface. Therefore, it is much easier for the farmer to evaluate feeding response when using a floating feed. However, floating feed often costs more. It is therefore up to the farmer to decide if floating feed is worth the added expense by evaluating fish performance and feed conversion.