FCRSOFT
What Is FCR?
What is FCR (feed conversion ratio), how is it calculated and how do economic and biological FCR differ? Formula, worked example and ways to track FCR.
FCR (feed conversion ratio) shows how many kilograms of feed a fish eats to gain 1 kg of live weight. The lower the FCR, the more efficiently the feed is used.
How is FCR calculated?
FCR is found by dividing the total feed given in a period by the live weight gain in the same period.
FCR = Total feed given (kg) ÷ Live weight gain (kg)
For example, if a cage received 15,000 kg of feed in a month and its biomass grew by 10,000 kg, FCR = 15,000 ÷ 10,000 = 1.5.
Economic vs. biological FCR
Economic FCR does not count dead fish in the weight gain and shows the farm’s real feed efficiency. Biological FCR adds the weight of dead fish to the gain and measures how well the fish used the feed. The higher the mortality, the bigger the gap between the two.
Why does FCR matter so much?
Feed usually makes up more than half of total production cost in fish farming. So even a 0.1 improvement in FCR means tonnes of feed and a significant cost saving at scale.
Free tool: FCR Savings Calculator
FCR vs. FCE
FCE (feed conversion efficiency) is the inverse of FCR and is expressed as a percentage: FCE = Weight gain ÷ Feed given × 100. If FCR is 1.25, FCE is 80%.
How do you track FCR?
- Determine opening and closing biomass with sample weighing.
- Record the feed given at every meal by cage or pond.
- Enter mortalities and harvest/transfer movements daily.
- Calculate and compare FCR weekly or monthly, unit by unit.
Frequently asked questions
What is a good FCR?
There is no single ideal value; it depends on species, system, temperature, fish size and feed quality. For example, 1.0–1.3 is common for trout and salmon, and 1.6–2.0 for sea bass and sea bream.
Can FCR fall below 1?
Yes. Dry feed is rich in energy and protein while most of a fish’s body is water, so in species such as salmon and trout FCR can approach or even fall below 1.
How often should FCR be calculated?
At least once a month per cage or batch, ideally after every sample weighing; weekly tracking is better for spotting deviations early.