About Fish Calories Calculator
Fish Calories Calculator is a free set of tools for people who keep fish. It turns general feeding guidelines into clear daily amounts in calories and grams.
Why this site exists
Most feeding advice online is vague. "Feed a pinch" means something different to every person. Other advice uses one formula for every fish. That fails when you keep a 2.5 g betta, an 80 g goldfish and a 1,000 g koi in the same house. A tiny fish eats a bigger share of its weight than a large one, and water temperature changes the amount again.
We built these tools to give each species its own range and to show the math. You see the result and the assumptions behind it. Then you decide what to feed.
What you can do here
- Use the fish calories calculator to estimate daily kcal for your species, size and water temperature.
- Use the fish feeding calculator to get grams per day, grams per meal and a feeding rhythm.
- Read the fish food nutrition table for protein, fat, fiber, moisture and energy.
- Use the fish food comparison tool to judge foods fairly, including moist foods that look weak on a label because of their water.
How the numbers are built
Every result follows the same four steps. First, each species has a typical feeding rate, written as a percent of body weight per day in dry food. Second, the tool adjusts that rate for life stage and goal. Juveniles get 1.8 times the adult rate, and seniors get 0.8 times. Third, it adjusts for water temperature, because fish are cold-blooded. Fourth, it converts the dry-food amount into kcal at about 3.6 kcal per gram, or into grams of the food you choose.
The calories calculator page shows each step with worked examples and a full table of species rates.
Where the data comes from
No lab has measured the calorie needs of every aquarium species. So we rank our sources in a clear order. Peer-reviewed research and national research bodies come first. Manufacturer labels and technical sheets come next. Experienced keeper consensus comes last. A claim that rests only on keeper opinion is treated as common practice and not as fact.
For background we point to the National Research Council book Nutrient Requirements of Fish and Shrimp (2011). It focuses on farmed species. That is why we call every aquarium range an estimate. Food values are typical figures for each food category. Real products vary, and the label on your food always wins.
What we cover and what we skip
We cover feeding amounts, feeding rhythm, food energy and food comparison for common freshwater fish and pond fish. We skip saltwater species until we can support the numbers. We also skip disease treatment, medicine and breeding programs. Those topics need an aquatic veterinarian or a specialist.
Who it is for
Beginners can get a safe starting portion in under a minute. Experienced keepers can compare foods or sanity-check a routine. Pond keepers can enter pond temperature for koi and goldfish. The tools are built for home aquariums and ponds and not for commercial farms.
The standards we follow
- We show assumptions. Every result lists how it was reached.
- We call an estimate an estimate. We do not claim lab precision for species that nobody has measured that closely.
- We admit gaps. Where good data does not exist, we say so and skip the made-up value.
- We keep it honest. We do not run fake reviews, invented credentials or paid placements.
- We stay independent. Nothing on this site is sponsored today. If we add ads or affiliate links later, we will label them clearly. They will not change any result.
How we review and correct
We check calculator assumptions when we add a species or a food. We change the date on a page when facts change and not for cosmetic edits. If you find an error, contact us with the page and a source if you have one. We fix verified errors promptly and update the page date.
What we are not
We are not a veterinary practice. Nothing here diagnoses, treats or prevents any condition. If your fish are bloated, refuse food for several days, lose weight or act strangely, contact an aquatic veterinarian. Do not delay care because of something you read here. The terms and conditions explain the full limits of the tools.
Your privacy
The calculators run in your browser. The species, weights and temperatures you enter stay on your device. We use Google Analytics to count visits and see which pages people use. Our privacy policy and cookie policy explain the details.
Who runs the site
The site is owned and run independently by its publisher. You can reach the publisher through the contact page. We do not publish under personal bylines, and we do not claim professional qualifications we cannot show.
Help us get better
If a range looks wrong for your fish, or you want a species or food added, tell us. Specific corrections with a source help most. We read every message.
| Item | Detail |
|---|---|
| Tools | Four free tools |
| Species covered | 9 freshwater species and groups |
| Foods covered | 9 common food types |
| Cost | Free, with no account |
| Where it runs | In your browser |
| Last reviewed | October 24, 2026 |