Productivity of fishponds can be increased by providing the fish with supplementary food. Manufactured fish feeds available in Africa are found in one or more of the following forms: Meal, crumble, dry sinking pellets, moist sinking pellets, and floating pellets.
Feed processing usually includes a number of steps, including grinding, mixing, binding together, fat coating, drying/cooling, crumbling, and bagging. In the African region, most on-farm feed preparations are made in small quantities, using improvised machinery that is operated either manually or mechanically, with outputs of not more than five 90-kg bags daily. Feed ingredients can be ground manually. The ingredients are then mixed in a hand-operated mixer. After preparation, feeds can be made into pellets using a pelleting machine
How to feed the fish
Some recipes for feed
Cottonseed cake – 37%, Wheat bran – 57%, Freshwater shrimp (Caradina spp.) – 6%, include a Vitamin premix. This is one of the different diet formulations that have been tested at Sagana Aquaculture Centre.
Some farmers are successfully using feeds they have mixed for themselves. Examples of mixes that are easily prepared and economical to use include:
• Mixture of 76% rice bran and 24% fish meal
• Mixture of dried freshwater shrimp (Caradina spp.) and maize bran, sometimes with some omena meal added.
To begin with, throw out small amounts of feed at a specific time of the day and observe the response. After the fish have accepted the prepared feed and learned when and where they will receive it from, they should become very enthusiastic feeders. Normally fish take about 15 minutes to consume the food.
You should be prepared to reduce the amount of feed per day when one or more of the following occur:
• Fish are clearly not consuming their normal amounts of feed
• Water temperatures are noticeably higher than normal for the time of year
• Dissolved oxygen levels are low
All of the above may occur simultaneously when you are nearing the end of a production cycle, especially if the planned harvest time is during the hot months.
When to feed your fish
Keep the following points in mind when feeding your fish each day:
• Tilapias have small stomachs and often browse all day long.
• The best time to provide supplementary feed is between 10 a.m. and 4 p.m., when the water temperature and dissolved oxygen are reasonably high.
• It is advisable to feed from the same position and time each day for each pond. The fish soon learn when and where they can expect a good meal.
• The feeder must be a reliable and dedicated person.
Feeding by hand has benefits
Some of the ways fish feed can be offered to fish include:
• Broadcast the feed into the water as you walk along the pond bank.
• Place the feed on a feeding platform or table under the water.
• Use a demand feeder, which releases fish food when the fish bump a lever.
• Use an automatic feeder, which releases or broadcasts feed at predetermined times.
• Neither the demand feeder nor the automatic feeder requires that an attendant be present at feeding time, but both need to be refilled regularly and periodically checked to be sure they are operating properly.
One benefit of feeding by hand is that the farmer has the opportunity to observe how well the fish are feeding, as well as how fast they are growing. Healthy fish usually eat enthusiastically, and any deviation from enthusiastic eating suggests that a problem may be developing.
The following are some reasons why fish such as the Nile tilapia may not feed as well as expected.
• The water is too cold.
• The dissolved oxygen level is too low.
• The fish may have died.
• The fish are ill.
• The feed is very heavy and sinks so fast you do not see the fish eating it.
How much feed do the fish need?
It is important to estimate how many fish fingerlings you have in your pond to properly calculate how much feed to give them. When you prepare the pond for stocking, keep a record on how many fish were stocked, and make frequent observations of the pond to know whether or not some fish have died.
A look at the table below will help you understand the amount of feed your fish require:
• The feed rations shown in the above table can be used for ponds stocked with tilapia or ponds with both tilapia and catfish (polyculture).
• The rations can be fed all at once or divided into two equal portions given in the morning and in the evening.
• For better feeding efficiency, weigh a representative sample of your fish every second week, using their actual weight to determine the amount to feed rather than an assumed weight.