PART OF THE AQUACULTURE GLOSSARY
Feed Conversion Ratio (FCR) shows how well fish turn feed into actual growth. For anyone farming fish at any scale, this one number often decides whether feeding is a smart investment or a slow money leak.
The Simple Math
FCR = total feed weight given ÷ total weight gained by the fish.
An FCR of 1.5 means it took 1.5 pounds of feed to grow 1 pound of fish. Lower is better, it means more of what you’re paying for turns into actual fish.
A Simple Example With Numbers
Say you feed your fish 150 pounds of feed over a season. They grow from 50 pounds total to 150 pounds total, a gain of 100 pounds. Your FCR is 150 ÷ 100 = 1.5. If a better feed got the same 100 pounds of growth using only 120 pounds of feed, your FCR would drop to 1.2, a real improvement.
Why FCR Changes So Much
Feed quality matters most. A higher-protein feed often costs more per bag, but it converts better, sometimes making it cheaper overall per pound of fish grown. Water temperature matters too, fish outside their comfort zone digest less efficiently no matter how good the feed is.
What a Rising FCR Tells You
If FCR gets worse over time, with no feed change, that’s worth investigating, not ignoring. It can point to:
- Overfeeding, fish aren’t hungry enough to use what’s given
- A health issue affecting appetite or digestion
- Water quality problems, especially low oxygen, which makes it harder for fish to use feed well
Tracking FCR Yourself
You need two numbers: total feed given, and total weight gained, over the same time period. Most casual pond owners skip this. For small commercial farms, it’s often the line between a profitable season and a break-even one.
FCR and Overfeeding
Overfeeding wastes money directly. It also adds more ammonia, since uneaten feed breaks down just like fish waste. Feeding to appetite, stopping once fish visibly slow down eating, usually beats a fixed feeding schedule for keeping FCR low.
FCR Changes by Life Stage
Younger, smaller fish generally convert feed less efficiently than mid-sized growing fish. Very large fish near harvest size also show worse FCR, since growth naturally slows down. This is part of why feed formulas change across a fish’s life, from fingerling to juvenile to full adult.
FCR Across Species
Different species convert feed differently by nature. Tilapia and catfish generally show better FCR than many ornamental species raised mainly for looks rather than growth speed.
The Cost Side of FCR
A lower FCR doesn’t always mean lower total cost. A premium feed with great conversion can still cost more overall than a cheap feed with worse conversion, depending on price per bag. What actually matters is cost per pound of fish produced, not just cost per bag of feed.
Related Terms
Fingerling · Water Temperature · Stocking Density
Related Memeilo Content
FCR as an Early Health Signal
Because FCR reflects how well a fish’s whole system, appetite, digestion, growth, is working together, a sudden shift in FCR often shows up before other, more obvious signs of illness or water trouble. Tracking it, even loosely, gives you a head start on catching problems early.
Even a rough monthly check, weighing a small sample of fish and doing the simple math above, beats not tracking FCR at all. It costs only a few minutes each time and gives you a real head start on catching feeding or health problems before they become visible.
Related Tools
Memeilo’s Fish Feed Formulation Calculator helps estimate the feed side of this equation, so you can compare your actual results against a reasonable starting target.
