Fish Calories Calculator and Feeding Guide
Know roughly how much your fish should eat, in calories and in grams, based on the species you actually keep.
Four tools, each on its own page
- Fish Calories CalculatorDaily kcal range from species, weight, temperature and food.
- Fish Feeding CalculatorGrams per day, grams per meal and a feeding rhythm.
- Fish Food NutritionProtein, fat, fiber, moisture and energy of common foods.
- Fish Food ComparisonCompare foods on a dry-matter basis, side by side.
Why one calorie formula does not fit every fish
A betta weighs a few grams. A koi can weigh over a kilogram. Small fish burn more energy per gram of body weight, so they eat a bigger share of their weight each day. A guppy takes 3 to 5 percent of its weight in dry food. An adult koi takes 0.5 to 1.5 percent. Temperature changes the picture again. Fish are cold-blooded, so they slow down in cool water.
That is why these tools work from species ranges. They then adjust for life stage, goal and water temperature. Every result shows its assumptions. Where good data does not exist, we say so and skip the precise-looking number.
How it works in three steps
- Pick your fish. Choose a species, a life stage and a real body weight. Add the number of fish and the water temperature.
- Choose your food. Flake, pellet, gel, frozen food and vegetables carry different amounts of energy per gram.
- Read the range. You get daily kcal, grams per day and grams per meal. Use it as a starting portion.
Pick your fish
Jump straight into the calculator with your species already selected.
GoldfishBettaGuppyAngelfishNeon tetraKoiCichlidPlecoGourami
How to use the results well
Treat the output as a starting portion. Feed it for two weeks and watch. Uneaten food, cloudy water and round bellies mean you should cut back. Thin bodies and constant searching mean you should add a little. The two-minute rule remains the best live check. Offer only what your fish finish in about two minutes.
Food matters as much as amount
Two foods can weigh the same and feed very differently. Frozen foods are mostly water. Pellets pack more energy per gram. Six grams of frozen bloodworms match the energy in one gram of flake. Browse the fish food nutrition table, or put two foods side by side in the food comparison tool.
Who these tools are for
Beginners can get a safe starting portion in under a minute. Experienced keepers can compare foods and 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.
What the tools cannot do
They cannot see your fish. Tank mates, algae grazing, food quality and health all change what a fish needs. They also do not diagnose illness. If a fish bloats, stops eating for several days or loses weight, contact an aquatic veterinarian. Read more about us and how we build the numbers.
Frequently asked questions
What is a fish calories calculator?
It estimates the daily food energy a fish needs from its species, size, life stage and water temperature. It gives a range to start from and not an exact requirement.
How accurate are the results?
They are estimates built on general feeding guidelines. Individual fish vary, so watch body shape and leftover food. Hold any new amount for two weeks before you judge it.
Which tool should I start with?
Start with the fish feeding calculator if you want grams per meal. Use the fish calories calculator if you want kcal. Use the nutrition table and the comparison tool when you pick or switch foods.
Can I use it for saltwater fish?
The current species list covers freshwater favorites. Marine species are not included yet, and we will not guess numbers we cannot support.
Does the site store my fish details?
No. The calculators run in your browser, and the values you enter stay on your device. There is no sign-up.
Is it free?
Yes. All four tools are free to use, with no account and no limit on how often you run them.