More and more people are considering fish farming as a way to utilize their land. The costs are generally less than the expenses of traditional agriculture, but the risks are high. One oversight or one unusual weather event can ruin a whole season's harvest. To reduce the risk of total loss and to increase profits, some farmers are considering polyculture fish farming.
Polyculture fish farming involves raising two or more complementary species in one pond. A successful polyculture operation will contain species that do not compete for food, mature at about the same rate and may complement each other's ecological habits.
Catfish are a popular breed raised by fish farmers. Catfish are generally bottom dwellers who feed on almost any plant or animal life that makes its way to the bottom. Tilapia, on the other hand, will feed anywhere within a pond. Catfish and tilapia will eat similar food, so the farmer only has to purchase and distribute one type of food. The tilapia will eat whatever they can at feeding time and the catfish will still get plenty of the food that falls to the bottom. The catfish will also eat any fry produced by the tilapia.
Even though two species have complementary ecological habits, they may not be good matches for polyculture fish farming. If the chosen species mature at different rates, they won't be ready to harvest at the same time. If one species is predatory, it may wipe out the other species over the course of the growing season. You can't raise prawns, which are harvested by draining the pond at the end of the season, with a species that reproduces and provides stock for the following season.
There are few rules about which species you should choose if you want to start a polyculture fish farm. The species to select will depend on where you live, how long the growing season is, what types of aeration you are able to provide, what types of food will allow you to turn a profit, what kind of food handling and distribution systems you possess, what species are available in your area, the volume of water in your operation, how much time you can allocate to maintenance and active participation in the operation and other considerations you will uncover along the way.
Aquaculture books and magazines can provide you with suggestions and instructions. Your local Extension Office may be able to provide you with information pertinent to your area of the country, as well as provide contact names of local fisheries and aquaculture suppliers.