By Joshua Kato
This is very important for fish farmers because most farmers do not know the right density or the amount of fish to be stocked in a pond.
Many think that they can get a lot of fish by stocking heavily not knowing that each pond has a maximum carrying capacity and once it is overstocked, the fish will not die but it will not grow. Overstocking will cause stunted growth of fish and this will automatically kill the market.
Farmers are advised to stock within 10 days after filling the pond with water. Fingerlings weigh between 7-10 grams. 2kgs per square metre for catfish is recommended, while 1kg is recommended for tilapia.
This means that if tilapia weighs 10 grams, you can stock as many as 100 fingerlings in a square metre. On the other hand, if catfish fingerlings weigh 10 grams and you need 2kgs, you stock 200 fingerlings per square metre.
Fish are fed on prepared fish feeds. The feed should be able to provide the nutrients required for the growth and survival of the fish. The amount of feed a fish can consume each day is determined by its body weight.
Normally, it is 5% of its body weight for newly stocked fingerlings. Feed percentages drop as the fish mature to at least 1% as they near full maturity.
If fingerlings weigh on average 45 grams after 4-5 weeks in the pond, the total percentage of feed is 3.8% x 45grams=1.7g. Well-fed fish will have gained at least 122 grams by the 9th week. By this time, each should be feeding around 3% of their body weight which is around 3.7 grams.
You then multiply feeds per fish by the number of fish in the pond to get the total amount of feeds that are dropped in the pond. Feeds must be dry and not mouldy before they are dropped in water. If well-fed, fish should be ready for harvest at 8 months.
Keeping off birds
Birds are one of the leading predators of young fish. Use fish nets and put them over each of the ponds. These prevent the birds from swooping into the ponds to ‘steal’ the fish.
To locate the fish nets, set up strong short poles on the sides of the pond and it is on these poles that the nets were tied, about a feet over the ponds.
Snakes are also known to feed on fish from ponds. If a farmer is not careful, snakes can easily make fish farming untenable. To keep off other predators like snakes, plant anti-snake herbs like tobacco around the fish ponds.