Fish Feeding Calculator
Find out how much food to offer per day and per feeding. Weigh the portion with a small kitchen or jewelry scale when you can. Eyeballing pinches is how most overfeeding starts.
How the estimate works
The tool starts from a species feeding rate, written as a percent of body weight per day in dry food. It scales that rate for life stage, goal and water temperature. Then it turns the dry-food amount into grams of the food you chose, so frozen food gets a bigger number than pellets. The fish calories calculator explains each step and lists the rate for every species.
A simple five-step feeding method
- Start with a range. Small fish eat a bigger share of their weight than large fish. Guppies take about 3 to 5 percent of body weight in dry food each day. Adult koi in warm water take 0.5 to 1.5 percent.
- Add up the group. Ten guppies at 0.6 g each weigh 6 g. At 3 to 5 percent, the group needs about 0.18 to 0.30 g of dry food a day. That is tiny, which is why a scale helps.
- Split it into meals. Adults do well on one or two meals. Smaller portions also keep the water cleaner.
- Run the two-minute check. If the fish finish in about two minutes, the amount fits. Anything left after three minutes means you should cut back.
- Check the body. A firm, slightly rounded belly is normal. A sunken belly means add a little. Stringy waste and cloudy water mean reduce.
Sample daily amounts
These figures use the tool's feeding rates for adult fish in water at the ideal temperature.
| Fish | Total weight | Rate | Dry food per day |
|---|---|---|---|
| 1 adult goldfish | 80 g | 1 to 2% | 0.8 to 1.6 g |
| 1 betta | 2.5 g | 2.5 to 4% | 0.06 to 0.10 g |
| 6 neon tetras | 1.2 g | 3 to 5% | 0.04 to 0.06 g |
| 2 angelfish | 50 g | 1.5 to 3% | 0.75 to 1.5 g |
How often to feed
| Fish or situation | Meals per day | Notes |
|---|---|---|
| Most adult fish | 1 to 2 | Small meals keep the water cleaner. |
| Goldfish | 1 to 2 | No true stomach, so small meals matter. |
| Small fast fish such as guppies and tetras | 2 to 3 | They do well on small, frequent meals. |
| Juveniles | 2 to 3 | They grow fast and need more food for their size. |
| Fry | 3 to 5 | Food must be small enough to swallow. |
| Seniors | 1 to 2 | Appetite and needs drop with age. |
| Koi above 65°F | 2 to 4 | Use regular protein-rich pellets. |
| Koi at 50 to 65°F | 1 or fewer | Use a light cool-weather food. |
| Koi below 50°F | 0 | Do not feed. |
How to measure very small portions
A jewelry scale reads to 0.01 g. Weigh ten pellets and divide by ten to learn the weight of one. After that, count pellets and skip the scale. For flakes, weigh one portion, tap it into a small spoon and mark the level. Use that spoon every day. Tell everyone in the house the exact amount, because family members who feed on the side cause many overfeeding problems.
Signs you feed too much
- Food on the gravel three minutes after a meal.
- Cloudy or smelly water.
- Long, stringy waste trailing from the fish.
- Bloated bellies, or fish hanging near the surface after meals.
- Algae that returns days after you clean.
If you see these signs, cut the next portion by about one third. Net or siphon out the leftovers. Change 25 to 30 percent of the water, and test for ammonia and nitrite. Hold the new amount for two weeks before you judge it. Uneaten food breaks down into ammonia, and a cycled tank should read zero ammonia and zero nitrite.
Signs you feed too little
A sunken belly, a pinched back and fish that never rest can point to too little food. Add small amounts and watch the shape of the fish for two weeks. Tank mates can also starve a slow fish even when the total looks fine. Feed in two spots, or feed after the lights go out for night feeders such as plecos.
Should you fast fish one day a week?
A weekly fasting day is optional. One day in seven cuts about 14 percent of the food over the week and gives the gut time to clear. Healthy, well-conditioned adults in stable water can usually skip a day. Goldfish, cichlids and large community fish often handle it well. Fry, juveniles, thin fish and sick fish should not fast. Small fish with fast metabolisms do better with a light day at half the usual portion.
Pick one fixed day. Feed the normal amount on the other days and do not double up the next day. Check body shape after a month, and stop if the fish look thin.
Feeding while you are away
Many healthy adult fish cope with a trip of up to a week without food. Longer trips need a plan. Weigh one day of food and seal it in a small bag. Make one packet for each day away, and ask a helper to open one packet a day. Packets beat the instruction "feed a little", because a kind helper will often overfeed.
If you use an automatic feeder, test it at home for two weeks and weigh what it drops. Pellets often work better than flakes in feeders. Change some water a day or two before you leave, and check the heater and filter. For trips longer than two weeks, ask a trusted friend, a pet sitter or a local fish club member to visit.
Feeding baby fish
Fry need three to five very small meals a day. Livebearer fry such as guppies take finely crushed flake or powdered fry food right away. Egg-layer fry often start on infusoria, microworms or newly hatched baby brine shrimp. Food must fit the mouth, or a fry will starve beside a full bowl. Use the juvenile setting as a starting point, then judge by eye. Look for slightly rounded bellies and no leftover food after a couple of minutes. Siphon leftovers every day.
Feeding pond koi and goldfish through the seasons
Feed by the thermometer and not the calendar. Above 65°F, koi take regular protein-rich pellets in two to four small meals. Between 50 and 65°F, switch to a cool-weather food once a day or less. Below 50°F, stop. In spring, wait until the water holds above 50°F for several days, and measure the water in the morning. Then offer a small amount every other day and build up slowly. Cold water slows the gut, so food can sit undigested for a long time.
Limits of any feeding chart
A chart cannot see your fish. Tank mates, algae grazing, food quality and body condition all change what a fish needs. Use the amount as a starting portion and hold it for two weeks. Then adjust by small steps based on belly shape, leftover food and water clarity.
Frequently asked questions
How much should I feed my fish?
Offer only what your fish finish in about two minutes. This calculator gives a gram range to start from, and the two-minute check keeps you honest. Weigh the portion on a small scale whenever you can.
How often should I feed aquarium fish?
Most adult fish do well with one or two small meals a day. Small fast fish such as guppies and tetras often do better on three. Juveniles need two or three meals. Fry need three to five tiny meals.
Should I skip a day of feeding?
Many healthy adult fish do fine with one fasting day a week. Do not fast fry, juveniles, sick fish or fish that are already thin. The evidence comes mostly from keeper experience, so treat it as common practice and not as a rule.
Why is the amount of frozen food so much larger?
Frozen foods are mostly water, so they carry fewer calories per gram. The tool converts the dry-food amount into grams of the food you pick. About 6 g of frozen bloodworms match 1 g of flake.
What happens if I overfeed my fish?
Uneaten food rots and turns into ammonia, which harms fish. Heavy feeding can overload the filter bacteria. You may see cloudy water, food on the gravel, long stringy waste and algae that returns within days.
Can fish go a week without food?
Healthy adult fish in an established tank usually cope with a few days, and many keepers skip feeding on a trip of up to a week. Fry, juveniles and thin fish need food on schedule.
Do I feed less in winter?
Yes, if your water cools. Cooler water slows appetite and digestion, and the tool lowers the amount when you enter a lower temperature. Pond koi stop eating near 50°F.