Integrated Livestock-Fish Farming
Senior 3 · Agriculture
Integrated Livestock-Fish Farming
Lesson 3 of 4
25 min
Let's begin
Two farmers stock the same number of fingerlings in identical ponds. Six months later one harvests plump fish of 300 g; the other finds small, thin fish, and a few dead ones floating at dawn. The difference is daily management: keeping the pond and its animal house in repair, keeping the water at the right shade of green, and giving the right amount of feed for the number, size and species of fish. In 2024–25 RAB trained fish farmers in exactly these skills, on feeding, fish handling and protection against diseases (MINAGRI, Annual Report 2024–2025).
Definition
Supplementary feed: feed given to fish in addition to the natural food (plankton, insects, plants) in the pond.
Feeding rate: the daily amount of feed as a percentage of the total mass of fish in the pond.
Biomass: the total mass of all the fish in a pond:
Sampling: catching and weighing a small group of fish to estimate their average mass.
Secchi disk: a disk painted in black and white quarters, lowered on a marked string to measure how clear the water is.
Dissolved oxygen: oxygen gas dissolved in the water, which fish breathe through their gills.
| How often | Task |
|---|---|
| Every day | check the water level; clear the inlet and outlet screens; check that manure enters the pond a little at a time; look for fish gasping at the surface early in the morning; feed; record feed given and any deaths |
| Every week | walk the dikes looking for leaks, cracks and burrows (rats, crabs); repair at once; cut the grass on the dikes; pull out floating and rooted water weeds; clean the animal house |
| Every month | sample the fish and adjust the feed; check the spillway; repair the animal house floor and the manure channel |
| After each harvest | drain and dry the pond, remove surplus mud, repair the dikes, lime and refill (Lesson 4) |
Manure and fertilisers feed phytoplankton, the base of the pond's food chain. In an integrated farm the animal house supplies manure every day; on other farms manure or compost can be put in a fenced compost crib in one corner of the pond, or small amounts of urea and DAP dissolved in water and spread over it. The aim is a pond the colour of fresh green pea soup, not clear and not dark.
Check it with a Secchi disk (Figure 19), or with the elbow test: push your arm into the water up to the elbow. If you can just see your palm, the plankton is about right; if it disappears before your wrist is under, there is too much; if you can see it clearly, there is too little.
Figure 19. Reading pond water with a Secchi disk (typical guide values).
Too much fertiliser or manure makes a thick bloom of algae. At night the algae and the bacteria rotting the manure use up the oxygen, so before dawn fish gasp at the surface and may die. Then: stop adding manure and feed, let in fresh water, and splash or stir the surface.
Fish need a smaller share of their body mass as they grow:
| Average mass of the fish | Daily feed, as a percentage of biomass (typical) |
|---|---|
| 1 to 10 g (fry and small fingerlings) | 8 to 10% |
| 10 to 50 g | 5 to 6% |
| 50 to 100 g | 3 to 4% |
| 100 to 250 g | 2 to 3% |
| over 250 g | 1.5 to 2% |
To work out a daily ration: (1) estimate the number of fish (fish stocked × survival); (2) sample 20 to 30 fish and find their average mass; (3) biomass = number × average mass; (4) daily feed = biomass × feeding rate. Use the lower end of the range in a pond that is well fertilised by animals. Divide the feed into two or three meals, given at the same place and times; it should be eaten within about 15 to 30 minutes. Cut feeding when fish gasp in the morning, when the weather is cold and cloudy, or when feed is left over.
Worked example 1: the daily ration
Problem. A 300 m² pond was stocked with tilapia at 3 per m², and about 90% have survived. A sample shows an average mass of 50 g. Using a feeding rate of 4%, how much feed is needed each day, and how much per meal if fed twice?
Solution.
Answer: about 1.6 kg a day, in two meals of about 0.8 kg.
Worked example 2: adjusting after sampling
Problem. A month later the farmer in Worked example 1 nets 25 fish, which weigh 3.0 kg together. The feeding rate for this size is 2.5%. What is the new daily ration?
Solution.
Answer: about 2.4 kg a day. The fish have more than doubled their biomass, so a ration left unchanged since last month would underfeed them.
Warning
Common mistakes. (1) Feeding by guesswork instead of by biomass: overfeeding wastes money and fouls the water; underfeeding stunts the fish. (2) Feeding the same amount for months although the fish grow. (3) Adding manure and fertiliser while fish gasp at dawn. (4) Ignoring small leaks and burrows until the dike breaks. Never wade into a pond alone, and never let children near deep ponds.
Tip
Exam technique: for feeding questions, always write the chain number → survival → biomass → rate → daily feed → per meal, with units at each step.
Access Agriculture: "Stocking fingerlings (Summary)". Note how fingerlings are counted, carried and let into the pond gently, so that the numbers used in feeding sums are right from the start.
Practice
Key points
Sources and credits
Written by Ganzaa: the text, the tables, Figure 19 and the worked examples. Feeding rates, protein levels and Secchi readings are typical guide values; follow the feed label or your fisheries officer's advice.
