Tool

Fish feed calculator by biomass

Quick answer

Multiply the number of fish by their average weight to get biomass. Apply the feeding rate for that size: SRAC Publication 282 suggests 10% to 5% of biomass per day for 5 to 18 g tilapia, 5% to 3% for 18 to 75 g, and 3% to 1.5% from 75 g to market. Divide the daily ration by the number of feedings to see how much to give each time.

Written byVeterinário Raiz TeamUpdated onOctober 14, 2026

Enter how many fish you have and their average weight in ounces. The tool suggests a feeding rate for that size and returns pounds of feed per day, per feeding and per month.

The math runs in your browser. Nothing you type is sent, saved or shared.

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How the math works

Biomass = number of fish × average weight (ounces ÷ 16 = pounds).
Feed per day = biomass × feeding rate (% of body weight).
Per feeding = daily feed ÷ number of feedings.
Feed in 30 days = daily feed × 30; add the price per pound to see the cost.

Rates come from Table 1 of SRAC Publication No. 282, Tank Culture of Tilapia. The table is in grams, so the tool converts your ounces (1 oz = 28.35 g) to pick the size class.

Limits

These are guidelines for tilapia in tanks. Other species and cooler water need lower rates; follow your feed label. If you run a backyard system, see aquaponics system for beginners.

Frequently asked questions

How do I find the average weight of my fish?

Net a sample, weigh them together and divide by the number of fish. Repeat every few weeks, since the feeding rate drops as the fish grow.

Which value of the SRAC range does the tool use?

The low end of each range, for example 1.5% for fish over 75 g. Move toward the high end for fish at the start of a size class if they clean up the feed and water quality holds.

What if water quality gets poor?

SRAC 282 notes that in systems without good solids removal and aeration, water quality often fails before the full ration is fed. The manager can then reduce or suspend feeding or begin water exchanges.

Sources

SRAC Publication No. 282, Tank Culture of Tilapia (revised June 2009), Table 1: suggested feeding rates for tank-cultured tilapia by average weight — 20–15% of biomass/day post-hatch to 0.5 g, 15–10% at 0.5–5 g, 10–5% at 5–18 g, 5–3% at 18–75 g, 3–1.5% at 75–150 g and from 150 g to market↗

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