Fish culture involves the controlled cultivation and harvesting of fish for either family consumption or sales in the market. Although fish culture is over thirty years old in Nigeria, it is yet to develop relatively when compared with arable agriculture and livestock production.
A wide range of practices exist in culturing fish. Fish can be cultured in marine (sea water), brackish (mixture of sea and fresh water i.e. lagoons) or fresh water (rivers, streams and lakes in the inland), depending on the facilities designed to serve as enclosures in rearing, fish can be grown in earthen ponds, concrete tanks, cages, pens, or run ways. The level of management practices can make a fish farm to be extensive or intensive system. When species combinations are taken into consideration, culture systems can be either monoculture (rearing only one type of fish) or polyculture (rearing two or more species of fish together).
A fish pond is an enclosure (earthen or concrete) built to retain water for the purpose of growing fish. Wooden troughs, fibre glass and plastic tanks are other media of growing fish. Growing fish in ponds from which they cannot escape allows feeding, breeding, growing and harvesting of the fish in a well-planned way.
POND CULTURE SYSTEM
Fish ponds can be classified mainly using the following criteria:-
- Construction design
- Level of management input
- Fish culture practices
- Scale of production
- Earthen Ponds: These are constructed by digging soil in a carefully selected site that is good enough to retain water for fish culture. Where the soil structure is weak to retain adequate water, dug out earthen ponds can be reinforced with concrete to make it suitable for fish culture.
- Concrete/Embarkment Ponds: These are pond constructed on the ground that is above the ground surface with concrete wall. Concrete ponds can be used to raise fish in a place with porous or sandy soil or within living premises.
- Barrage Ponds: This is a type of pond constructed by building a wall across a stream running in a low valley. The wall ensures enough water retention for fish growth.
- Diversion Ponds: Ponds supplied by water diverted from a river/stream through a channel are called diversion ponds. Such pond, is also known as Relief Pond.
- Rosary Ponds: These are ponds built in a string and each drains into the other and are managed as a single unit due to their water connection.
- Parallel Ponds: These are ponds located in an area with each having its own inlet and outlet.
Level of Management Input
Depending on the level of management inputs, especially in feeding, fertilization and liming, pond culture systems can be classified as Extensive, Semi-Intensive or Intensive.
- Extensive Culture System: When food base in a pond is exclusively naturally occurring without supplementation (either by feeds or fertilizer), the culture system is an extensive one. This practice is popular with small-scale producers.
- Semi-Intensive Culture System: In this system, there is occasional supplementary feeds addition and natural productivity is augumented by manures.
- Intensive Culture System: This demands a higher level of management input. Feeds and fertilizers are intensively applied following appropriate recommended rates. Suitable liming materials like agricultural lime are also applied to stimulate productivity and disinfect the pond of parasite and diseases. Fish grow very fast when intensively managed and grow least in extensive management. Most commercial farms adopt this approach.
Fish Culture Practices
Pond can be classified as monoculture or polyculture.
- Monoculture: This is the practice of culturing only one species of fish in a pond unit. Under monoculture, a farmer may grow only clarias in the pond. He will be able to know more about the management of clarias than other fish species.
- Polyculture: This is the practice of culturing more than one species of fish in the same pond. Fish yield under polyculture can be higher and foods in the pond properly utilized, since the different fish species exploit food at different trophic levels.
Scale of Production
- Homestead/Backyard Ponds: This is a fish pond that is managed to augument family protein intake. The size of such a pond could vary according to land space available e.g. 10m × 10m.
- Commercial Fish Ponds/Farms: This usually have an area of land not less than 0.25 hectare under culture. Such a farm will demand more attention from the fish farmer, since income generation is the major purpose behind its establishment. Concrete tanks units of not less than 200m2 can also be intensify as commercial ventures.
Having an understanding of pond fish culture is an essential factor in determining the level /scale of production that one can engaged in for profitability and sustainability.
Iyobosa Omoregbe is an Aquaculture Trainer at The Ark Shore Konsults (T.A.S.K.). He holds a Master’s degree in Fisheries Management from the University of Benin, Nigeria.