Feed Is Your Biggest Cost
And the only one you can really control every day
In intensive farming, feed absorbs most of the running cost. A small difference in feed efficiency multiplies into a large difference by the end of the cycle. That is why feeding is not just scattering, it is measuring.
The two numbers you have to master are the feeding percentage of fish weight, and FCR, the feed conversion ratio.
| Fish size | Feed per day | Frequency | Feed protein |
|---|---|---|---|
| Under 1 gram | 10 to 15 percent of weight | 5 to 6 times | 40 percent and up |
| 1 to 5 grams | 5 to 10 percent of weight | 4 to 5 times | 35 to 40 percent |
| 5 to 20 grams | 3 to 5 percent of weight | 4 times | 32 to 35 percent |
| 20 to 100 grams | 2 to 3 percent of weight | 3 times | 30 to 32 percent |
| Over 100 grams | About 2 percent of weight | 2 to 3 times | 28 to 30 percent |
Sampling, How to Know Fish Weight Without Weighing Them All
Ten minutes every ten days
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Take samples from several spots, not one place
Net from three to four different spots, including the edges and the middle. Large and small fish are not spread evenly across the pond.
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Take at least thirty fish
With fewer than that, one large fish that happens to be netted will shift the average too far.
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Weigh them all at once, then divide by the number of fish
For example, 30 fish weigh 2.4 kg. The average body weight, or ABW, is 2,400 grams divided by 30, which is 80 grams per fish.
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Estimate how many fish are still alive
If you stocked 2,000 fish and you estimate a survival rate of 90 percent, the number of fish now is about 1,800.
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Calculate the biomass and today's feed dose
The biomass is 1,800 fish times 80 grams, which is 144 kg. At 80 grams the dose is 3 percent, so today's feed is about 4.3 kg split into three feedings.
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Repeat every ten days and adjust
Fish keep growing, so the dose that was right last week is already too small this week. This is why sampling has to be regular, not once at the start.
FCR, the Number That Judges All of Your Work
How many kilograms of feed to produce one kilogram of fish
FCR is calculated by dividing the total feed used by the weight the fish gained. If you use 300 kg of feed and the fish weight rises from 20 kg to 220 kg, the gain is 200 kg, so FCR equals 300 divided by 200, which is 1.5.
The smaller the number, the more efficient. FCR is not just a measure of feed, it is a mirror of your whole management. Bad water, late grading, and overfeeding all show up as an inflated FCR.
| FCR | Assessment | Usually means |
|---|---|---|
| Under 1.0 | Suspicious, recheck the math | Natural feed or floc is being eaten as well, or the fish count is wrong |
| 1.0 to 1.3 | Very good | Tidy management, the biofloc is working and contributing feed |
| 1.3 to 1.6 | Good, a reasonable target | Day-to-day management is right |
| 1.6 to 2.0 | Still acceptable | Some feed is wasted or growth is uneven |
| Over 2.0 | Needs fixing | Overfeeding, bad water, or many fish dying without being recorded |
The most common feeding mistakes
Feeding at the wrong hour
Do not feed when oxygen is low, especially at dawn and in the late afternoon before dark. Fish that eat need more oxygen to digest.
Scattering it all at once, not gradually
Scatter a little at a time while you watch. Stop as soon as the fish start to lose interest in striking. Feed that sinks uneaten turns straight into ammonia.
Not adjusting to the weather
When it is cloudy, raining, or the temperature falls, the fish's appetite drops. Reduce the dose, do not force it.
Storing feed carelessly
Damp pellets grow fungus and lose nutritional quality. Store them in a dry place, on a pallet, and use them up within one to two months of opening.
Questions About This Module
What participants ask most often
What is the daily catfish feed dose?
It is worked out as a percentage of the weight of all the fish, not from the number of fish. Fish under 1 gram get 10 to 15 percent of their weight, 5 to 20 grams get 3 to 5 percent, 20 to 100 grams get 2 to 3 percent, and over 100 grams about 2 percent.
For example, 1,800 fish with an average body weight of 80 grams means a biomass of 144 kg. At a 3 percent dose, the feed for that day is about 4.3 kg split into three feedings. The number changes as the fish grow, so you have to sample again every ten days.
How do you calculate FCR?
Divide the total feed used by the weight the fish gained. If you use 300 kg of feed and the fish weight rises from 20 kg to 220 kg, the gain is 200 kg, so FCR equals 300 divided by 200, which is 1.5.
A reasonable target is 1.3 to 1.6. Below 1.3 is very good and usually happens because floc is being eaten as well. Above 2.0 means something needs fixing, usually overfeeding, poor water quality, or deaths that were not recorded.
How many times a day should fish be fed?
The smaller the fish, the more often. Fingerlings under 1 gram are fed five to six times a day, 5 to 20 gram fish four times, and fish over 100 grams only two to three times.
Avoid the hours when oxygen is low, dawn and just before dark, because digesting feed demands extra oxygen. Scatter a little at a time while you watch, then stop as soon as the fish start to lose interest in striking.
Why will my fish not eat?
Check the water first, not the feed. Low oxygen, high ammonia, high nitrite, or a sharp pH shift all suppress appetite before any other symptom shows.
Other common causes are a temperature drop from rain, a recent change of feed brand, feed that has gone damp and moldy, or fish that were just graded. If the water is normal and it lasts more than two days, only then suspect disease.
When do you sample and how?
Every ten days. Net fish from three to four different spots, take at least thirty of them, weigh them all at once, then divide by the number of fish to get the average body weight.
While the fish is in your hand, check its fins, gills, and body surface. Many diseases are first spotted during sampling, long before any fish dies. Healthy gills are bright red, not pale or brownish.
All the modules can be read in order or skipped through as needed. See the fish farming training list, or all training tracks.