How much, how often, and what to feed 28 aquarium species.
Fish feeding looks simple — drop pellets in, fish eat them, done. In practice it's the number-one cause of preventable fish death in beginner tanks, because the right amount and frequency varies dramatically between species. A betta needs 6–8 pellets a day in two meals; an anthias on a reef needs 3–4 small meals; a pleco needs almost nothing but algae and driftwood. Get the schedule wrong and you'll see one of two outcomes: bloated, constipated fish with swim-bladder issues, or starving fish that fail to colour up or grow.
How often should I feed my fish? A species-by-species summary
The default for healthy adult tropical fish is two feedings per day, with what the fish can consume in 60 seconds each meal. Here are the major exceptions:
- Bettas: 2× daily, 3–4 pellets each meal, one fast day per week.
- Goldfish (fancy): 2× daily, sinking pellets only, weekly blanched pea day.
- Corydoras & bottom dwellers: 1× daily, sinking food after lights-out so other fish don't steal it.
- Anthias (marine): 3–4× daily — they're adapted to constant plankton grazing on reefs.
- Tangs & herbivores: Nori sheet clipped in the tank for constant grazing, plus 1–2 pellet feedings.
- Plecos & algae-eaters: 1× daily evening feed of algae wafers; supplement with blanched courgette weekly.
- Shrimp & snails: Tiny pinch every 2–3 days. They graze biofilm constantly — overfeeding kills them faster than starvation.
- Juveniles & fry (all species): 3–5× daily smaller meals for steady growth.
For your specific species, run the calculator above — it returns the schedule, suggested clock times, food types, and species-specific notes in one click.
The 60-second rule: how much to feed
Regardless of species, the universal portion-size guide is the 60-second rule: feed only what your fish consume in about a minute. Food still floating after 90 seconds is overfeeding. Net it out (it'll otherwise decay into ammonia) and reduce the next meal by 20%.
This rule beats every "X pellets per fish" formula because it self-adjusts to:
- Fish appetite (lower in cold months, higher when breeding)
- Water temperature (warmer water = faster metabolism = more food required)
- Group size (more fish = more competition = faster consumption)
- Activity level (post-water-change fish eat more enthusiastically)
Flakes vs pellets vs frozen vs live: which fish food is best?
A healthy diet rotates between food types. Each has a purpose:
| Food type | Best for | Frequency | Pros | Watch out for |
|---|---|---|---|---|
| Quality flakes | Surface & mid-water feeders (guppies, tetras, danios) | Daily staple | Convenient, balanced nutrition | Loses nutrients fast after opening — buy small tubs |
| Sinking pellets | Bottom dwellers, cichlids, larger fish | Daily staple | Reaches floor-feeders, sized to mouth | Match pellet size to species — too big = ignored |
| Frozen bloodworms | Carnivores: bettas, cichlids, killifish | 1–2× per week | High protein, brings out colour | Avoid in excess — can cause bloat |
| Frozen brine shrimp / mysis | Almost all species | 1–2× per week | Universal protein boost, gut-loadable | Thaw before feeding — never drop in frozen |
| Algae wafers | Plecos, otocinclus, herbivorous bottom feeders | Daily for herbivores | Plant-based nutrition | Don't substitute for vegetables long-term |
| Live food | Conditioning breeders, picky species | Occasional treat | Triggers natural hunting behaviour | Disease vector — culture your own or buy clean |
| Vegetables (blanched) | Plecos, mollies, goldfish, herbivores | 1–2× per week | Cheap, fibre-rich, prevents constipation | Remove uneaten portions after 24 hours |
Common feeding mistakes — and how to avoid them
- Overfeeding. If your water is cloudy, your algae is blooming, or your nitrate climbs faster than expected — you're overfeeding. Halve your portions for two weeks.
- One food only. Even the best flake doesn't cover every nutritional need. Rotate at least two types of food, and supplement with frozen 1–2× per week.
- Wrong food zone. Surface flakes for bottom-dwelling corys means they starve. Sinking pellets for surface bettas means they ignore the food. Match food behaviour to fish behaviour.
- Tropical food for goldfish. Wrong nutrient balance. Goldfish need goldfish-specific food — they're cyprinids, not characins.
- Feeder fish for predators. Live feeder goldfish carry disease and contain thiaminase, which damages predatory fish liver over time. Use frozen or pellet food instead.
- Never fasting. Most fish benefit from one day a week without food. Bettas, goldfish, and gouramis especially — it prevents constipation and lets their digestive systems reset.
Holiday feeding: what to do when you're away
Healthy adult fish in a cycled tank can comfortably go 5–7 days without food. They're cold-blooded and metabolise slowly. Three options for longer trips:
- Up to 1 week: Do a 30% water change before leaving, then leave the tank entirely. Skip food. The fish will be fine.
- 1–2 weeks: Hire a sitter, but instruct them to do nothing but observe and check the heater. No feeding. Overfeeding by a well-meaning friend kills more holiday fish than starvation.
- Longer trips: Auto-feeders work but are unreliable. Better: a sitter trained on a pre-portioned daily packet (one envelope per day), with strict instructions to feed exactly one and no more.
Pair this with the volume calculator
Feeding amounts in the calculator above are species-typical, not group-size-specific. If you have a tank full of 12 cardinal tetras, your total feeding needs are roughly 12× the per-fish portion. To make sure your tank can handle that bioload in the first place, run your dimensions through our aquarium volume calculator and read the stocking math article. Properly stocked tanks are easy to feed; overstocked tanks need disciplined portion control to stay stable.