How often to feed fish, and how much: a beginner's feeding guide

Most adult aquarium fish do well on one small meal a day, five to seven days a week: only as much as they finish in about two minutes. Young fish need smaller meals more often. Overfeeding is the most common mistake beginners make, but underfeeding happens too, usually because the fast, greedy fish eat everything and the shy or bottom fish get nothing.

The other common problem is feeding the wrong food: flakes for a fish that needs vegetables, or algae wafers for a fish that needs meat. A fish can eat every day and still slowly starve.

How to tell if feeding is going wrong

Signs of overfeeding (see overfeeding):

Food lying on the gravel or plants a few minutes after feeding.
Cloudy water, a bad smell, fuzzy mould on leftovers, a snail explosion or algae blooms.
Rising ammonia or nitrate, and round, bloated fish.

Signs of underfeeding:

A sunken or hollow belly, seen from the side or below.
A pinched or "knife-edged" back: viewed from above, the body behind the head looks thin and the spine stands out.
Head looks too big for the body.
Faded colour, slow growth, fish picking constantly at plants or glass, or fish fighting more than usual at feeding time.

Signs of the wrong food (malnutrition):

Fish that eat but stay thin, or lose colour over weeks.
Bent spines in young fish (vitamin C deficiency is a classic cause), poor growth, or weak fry.
Plant-eating fish chewing your plants to stubs; meat-eating fish ignoring vegetable wafers.

When it's a problem

Normal: fish rush to food, eat it within a couple of minutes, and have gently rounded bellies. Bottom fish come out at dusk or after lights-out to eat.
Early: one fish is a bit thinner than the others, or there's some leftover food most days.
Serious: a fish with a sunken belly and pinched back, or water quality falling because of uneaten food.
Urgent: a fish that has stopped eating entirely. Not eating is usually a sign of illness or bad water, not a feeding problem; test the water and see fish dying or betta not eating.

What to do right now

Find out what each fish actually eats. Look up every species you keep: is it a herbivore (plant eater), omnivore (eats both) or carnivore (meat eater)? Does it feed at the surface, in mid-water, or on the bottom? Is it active by day or by night?
Watch a whole feeding for two or three minutes. Who eats? Who misses out? Where does the food end up?
Remove leftovers after about five minutes with a net or siphon.
Feed more than one spot at once. Drop food at both ends of the tank so the bullies can't guard all of it.
Feed the bottom fish separately. Drop sinking pellets or wafers after the top fish are busy eating flakes, or after the lights go out.
Look at thin fish closely. If one fish stays thin while eating well, it may have internal parasites or a disease rather than a food problem; see camallanus worms and flukes.

What to do next: feeding by fish type

Type of fish	Examples	What to feed
Surface feeders	Hatchetfish, bettas, killifish, guppies	Floating flakes or small floating pellets; small live or frozen foods such as daphnia or baby brine shrimp
Mid-water feeders	Tetras, rasboras, barbs, angelfish	Slow-sinking flakes or micro pellets, plus frozen foods a few times a week
Bottom feeders	Corydoras, loaches, plecos	Sinking pellets, wafers or gel foods, fed where they live, often at lights-out
Herbivores	Bristlenose plecos, many African cichlids, mollies	Food based on algae or spirulina, plus blanched vegetables
Carnivores	Bettas, zebra plecos, many killifish, puffers	High-protein pellets plus frozen bloodworm, brine shrimp or mysis
Omnivores	Most community fish, goldfish	A good flake or pellet, with both meaty and vegetable extras

Vary the menu. Use a good staple food plus two or three others through the week (frozen, gel, vegetable). Variety covers gaps in any one food.
Fasting days: many keepers skip one day a week for adult fish. It's not essential, but it does no harm to healthy adults and helps the water. Don't fast fry.
Fry: baby fish have tiny stomachs and burn energy fast. Feed them small amounts three to five times a day, using foods small enough to fit their mouths (newly hatched brine shrimp, microworms, powdered fry food), and keep up with water changes, because fry tanks foul quickly.
Plecos need their own plan; see what do plecos eat.

Products that help

A quality staple flake or pellet sized for your fish: the everyday food.
Sinking pellets or wafers: for corydoras, loaches and other bottom fish that rarely reach floating food.
Gel foods: powders you mix with hot water to set into a jelly; good for bottom fish and plecos, and easy to pack with vegetables or protein.
Frozen foods (bloodworm, brine shrimp, mysis, daphnia): protein and variety, especially for carnivores and fussy eaters.
Vegetable or spirulina-based foods: for herbivores.
Feeding ring: a floating ring that keeps flakes in one place so they don't drift into the filter.
Feeding tube or long tweezers: to place food right in front of bottom fish.
Keep on hand: two or three different foods, and an airtight container. Buy dry food in small amounts: it goes stale and loses vitamins. Use it within about three months of opening; freezing is fine, a damp cupboard is not.

How to prevent problems

Use the two-minute rule as a starting point. Feed a pinch, watch, and add a little more only if it's all eaten. Keepers use anything from one to a few minutes; the point is that nothing should be left over.
Think small. A fish's stomach is roughly the size of its eye. A betta needs only a few pellets.
Feed once a day for adults, or two small meals if you prefer. Small, active fish and fry need food more often than large, slow fish.
Feed the tank you have, not the fish that beg. Fish always look hungry.
Feed at several spots and at lights-out for shy and nocturnal fish.
Stock compatible eaters. Very fast, greedy fish and slow, shy feeders in one tank make fair feeding hard.
Look at your fish's bellies every week. It's the best feeding gauge there is.

Why it happens

Fish are opportunists: in the wild, food is scarce, so they eat whenever they can and always act hungry. Beginners respond by feeding too much, which fouls the water. In a mixed tank, fast surface fish grab everything before slow or bottom fish can reach it, so the shy fish starve in a tank full of food. And many fish are sold with "community flakes" when they really need something else: plecos sold as "algae eaters" are a classic example. UF/IFAS notes that starvation is usually a husbandry problem, often after owners cut back food to fix water quality.

When to get help

If a fish stays thin after two or three weeks of careful, targeted feeding, it may have parasites or a long-term infection. Ask an experienced keeper or a fish vet.
If several fish develop bent spines, faded colour or poor growth, review the diet with a fish vet or experienced breeder of that species.
If your fish are bloated, see bloated fish.

In the game

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