Aquaponics Fish Tank, Grow Bed & Feed Rate Calculator

How it works

Daily feed = bed area × feed-rate ratio (40–50 g/m²/day leafy, 60–100 fruiting); fish biomass = feed ÷ feeding %; tank volume = biomass ÷ stocking density; fish count = biomass ÷ harvest weight; media volume = area × depth

An aquaponics system is balanced by nutrients, not by a fixed tank-to-bed ratio: the fish feed is the only input, so the daily feed that a bed of plants can use — the feed-rate ratio developed at the University of the Virgin Islands, roughly 40–50 grams per square metre per day for greens and up to 100 for fruiting crops — sets everything else. Dividing the feed by the percentage of body weight fish eat gives the standing fish biomass, the stocking density the operator can maintain with aeration gives the tank volume, and harvest weight gives the head count. Media beds double as the biofilter, which is why depth of 30 cm and a volume at least equal to the tank are the traditional guidance, and why raft systems add separate filtration.

Worked example

Four square metres of leafy greens at 45 g/m²/day need 180 g of feed a day; at 1.5% of body weight that is 12 kg of fish, a 600 L tank at 20 kg/m³ and 24 tilapia grown to 0.5 kg. The 30 cm deep bed holds 1,200 L of media — a 1:2 tank-to-bed ratio — and 100 plants at 25 per m².

Frequently asked questions