There are numerous systems that can be employed in the rearing of fish, for the Nigerian context we will only be looking at the following four types outlined below.
The act of fish farming is about raising fish commercially in tanks or enclosures for human consumption. There are different types of fish farms that utilize different aquaculture methods.
The first method is the cage system which use cages that are placed in lakes, ponds and oceans that contain the fish. This method is also widely referred to as off-shore cultivation and it is an open system. Fish are kept in the cage like structures and are “artificially fed” and harvested. The fish farming cage method has made numerous technological advances over the years, especially with reducing diseases and environmental concerns. However, the number one concern of the cage method is fish escaping and being loose among the wild fish population. This system of farming cuts away the expense of water management, the existing water body determines the water quality. Appropriate stocking density for this system is 150-300 fish stocked per cubic meter of confined space.
The second method is irrigation ditch or pond systems for raising fish. This basic requirement for this method is to have a ditch or a pond that holds water. Fresh water is run into the fish ponds in order to maintain an acceptable water quality, this is one of the most common method of fish farming in Nigeria. In this flow through system, fresh water is constantly running into the fish ponds replacing degraded water found in the ponds, this system has high water consumption and proper drainage is usually a problem with this type of systems. The stocking density is between 50-100 fish per cubic meter depending on the experience of the farmer.
Another offset of the above method is the dugout system or earthen ponds system, in this system the ground is dug and filled with water for the fish to be stocked in. Depending on the water source it could a closed to semi-closed system. Usually there is no water change in this system, but fresh water could be put in to replace water lost from evaporation and seepage. For natural ponds natural food supply with the pond can be increased through pond fertilization and the stocking density is about 20-100 fish per cubic meter due to the lack of water change, however for artificial dugout earthen ponds, the running of the ponds is similar to that of the concrete ponds and the stocking density is similar to that of the concrete ponds as regular water change is required.
The fourth method of fish farming is called Re-circulatory systems which is considered the largest scale method of “pure” fish farming. This approach is a sophisticated, high cost method of Catfish production, in this system, the water is purified and reused in a continuous cycle with little addition from an external water source to make up for lost water. It is a very efficient method, however the system is very expensive to run due to the constant need for power supply and frequent monitoring of water quality. The high cost is usually offset by a much higher production capacity and because of the constant clarity and high water quality, the stocking density is between 150-300 fish per cubic meter.
There are a number of different fish species that are raised on fish farms, the most common fish spices raised are salmon, carp, tilapia, catfish and cod. In Nigeria the most common and most profitable is the catfish due to its high resilience and strength. The business of catfish farming can be divided into 3 distinct areas that are capable of generating revenue either individually or in combination with each other.
The areas are as follows:
- Hatchery (Fingerlings and Juvenile production)
- Fish for consumption (Both live and processed dry fish)
- Feed production
In our next series, we will be looking at each of the areas in more context and the viability and profitability of each area as a functional business model in the Nigerian economy.