Fish farming has the potential to provide farmers with good returns, but success depends on more than stocking a pond with fingerlings and waiting for harvest time. Water quality, feeding, genetics, stocking levels and market planning all determine whether a farmer makes money or suffers losses. According to Jessy Lugya, an Aquaculture Research Officer at the National Agricultural Research Organisation (Naro) based at Ngetta ZARDI, many farmers pay attention to buying fish seed but ignore the environment in which the fish will grow. ‘Fish use dissolved oxygen, but you cannot measure it with your eyes. If you do not know the quality of your water, then you are not in business,’ Lugya says.
The invisible factor
Unlike livestock that farmers can easily observe, fish live in an environment where problems may remain hidden until losses begin. Water quality affects how well fish feed, grow and survive. Farmers should pay close attention to dissolved oxygen, temperature, pH and salinity. Dissolved oxygen is particularly critical because fish depend on oxygen in water to survive. Low oxygen levels often occur in the early morning hours when oxygen levels are lowest. ‘If you find fish looking up and gasping, it is an indication that there is no oxygen. It normally happens in the morning hours,’ Lugya says. When oxygen levels fall, farmers should respond quickly by improving water exchange and replacing some of the pond water with fresh water where possible. Proper pond preparation and avoiding overcrowding also help maintain good water conditions.
Overstocking reduces profits
One of the biggest mistakes farmers make is trying to maximise production by putting too many fish in a pond. Although stocking more fish appears to promise higher earnings, overcrowding creates competition for oxygen and feed. It also increases waste accumulation, slows growth and makes fish more vulnerable to disease. Mr Lugya says profitability does not come from having the highest number of fish in a pond but from producing healthy fish efficiently. ‘Farmers need to stock according to the size of the pond, availability of water and their ability to manage the fish,’ he says.
Managing feed costs
Feeding is one of the most expensive parts of fish production. Poor feeding practices can quickly turn a promising project into a loss-making venture. Farmers who overfeed waste money while also damaging water quality because uneaten feed decomposes and reduces oxygen levels. The amount of feed should depend on the age, size and number of fish in the pond. Farmers should also observe feeding behaviour because fish that stop eating may be showing signs of poor water quality or disease. For tilapia farmers, Mr Lugya advises harvesting at the right time. ‘Tilapia should be sold at around nine months. Keeping fish longer increases feeding costs and may reduce profitability,’ he says.
Quality fingerlings
The journey to a profitable harvest begins with the quality of fingerlings stocked in the pond. Mr Lugya says farmers should source fish seed from trusted hatcheries because good genetics produce faster-growing fish and better final sizes.