Calculator inputs
Example data table
| Fish | Avg weight | Temp | Species | Rate | Feedings/day | Daily feed | Per feeding |
|---|---|---|---|---|---|---|---|
| 100 | 150 g | 27°C | Tilapia | 3.0% | 3 | 450 g | 150 g |
| 60 | 450 g | 25°C | Catfish | 2.0% | 2 | 540 g | 270 g |
| 200 | 40 g | 29°C | Carp | 5.0% | 4 | 400 g | 100 g |
| 80 | 250 g | 16°C | Trout | 2.0% | 3 | 400 g | 133.3 g |
| 35 | 1.2 kg | 24°C | Koi | 1.2% | 2 | 504 g | 252 g |
Formula used
This calculator estimates the daily feed amount from total biomass and a feeding rate. The feeding rate is expressed as a percent of body weight per day.
- Biomass (g) = Fish count × Average weight (g)
- Daily feed (g) = Biomass (g) × (Feed rate ÷ 100)
- Adjusted daily feed (g) = Daily feed (g) × Safety factor
- Per feeding (g) = Adjusted daily feed ÷ Feedings per day
How to use this calculator
- Count fish in your tank, pond, or grow-out bin.
- Measure average weight from a small sample.
- Enter current water temperature and choose species.
- Select suggested or custom feed rate percentage.
- Choose feedings per day and a safety factor.
- Press Calculate, then download CSV or PDF.
Why feed rate is based on biomass
Feed plans work best when they scale with total biomass, not tank volume alone. Biomass is simply fish count multiplied by average weight. In practice, two ponds with the same number of fish can need very different feed if one stock is heavier. This calculator converts your inputs to grams, then applies a percent-of-body-weight rate to estimate daily feed in grams and kilograms. This approach supports repeatable feeding across changing stock sizes.
Typical percent ranges and what they mean
Most garden systems operate between 0.8% and 5.0% of body weight per day, depending on fish size and season. Fingerlings often tolerate higher rates because growth and metabolism are faster, while larger fish commonly perform well at 1.0% to 2.5%. The suggested mode uses size bands to pick a baseline percentage, then adjusts it with temperature and goal multipliers.
Temperature influences appetite and waste
Water temperature changes digestion speed and oxygen demand. Warmwater species often peak around 24–30°C, while coldwater fish typically prefer roughly 12–18°C. Feeding heavily outside the comfort zone increases uneaten pellets and ammonia load. In the calculator, the temperature factor reduces the rate at low or high extremes to protect water quality and reduce waste.
Feeding frequency and pellet management
Splitting the daily ration into 2–4 feedings can reduce spikes in waste and improve consumption. For example, a 450 g/day plan becomes 150 g per feeding at three feedings. Use pellets that match mouth size: too large increases spit-out loss, too small can raise fines and cloud water. Aim for 5–10 minutes to finish each feeding, then adjust the safety factor.
Tracking performance with simple records
Record daily feed, weekly sample weights, and notes on behavior. If fish gain weight but water quality declines, reduce the rate or improve filtration and aeration. If fish clear feed quickly and growth stalls, increase gradually by 5–10%. Pair estimates with tests for ammonia, nitrite, and dissolved oxygen to keep growth steady and losses low.
FAQs
1) What does “% of body weight per day” mean?
It is the daily feed amount divided by total fish weight. A 2% rate means 20 g of feed per 1,000 g of fish biomass each day.
2) Should I always use the suggested rate?
Use it as a starting point. Adjust up or down based on leftover feed, growth checks, and water tests. Local conditions and stocking density can shift the ideal rate.
3) How accurate is average weight if I can’t weigh every fish?
Sample 5–15 fish, then average the weights. Re-sample weekly or biweekly. Consistent sampling improves accuracy more than trying to be perfect once.
4) Why does temperature change my feed plan?
Metabolism slows in colder water and stress increases at hot extremes. Feeding the same amount can create waste and ammonia. Temperature-based adjustment helps match appetite and digestion.
5) What safety factor should I choose?
Start near 1.00. Use 0.90 when water quality is marginal or fish leave pellets. Use 1.10 when fish finish quickly, oxygen is strong, and tests remain stable.
6) How do I use this for multiple tanks or cages?
Run the calculator per group, because weight and temperature can differ. Export CSV files for each group, then combine them in your spreadsheet for a whole-site feed total.