How to feed your aquarium fish
Feeding looks like the simplest part of fishkeeping, and it is the one most people get wrong. Fish always act hungry, so the instinct is to keep feeding, and that single habit causes more algae, worse water, and more dead fish than almost anything else. Here is how much to feed, how often, what to use, and how to keep your fish fed while you are away.
Published 21 June 2026 · Last updated 21 June 2026 · 12 min read
How much to feed
The rule that keeps tanks healthy: feed only as much as your fish completely finish in about 2 to 3 minutes, with nothing left settling on the substrate. A fish's stomach is roughly the size of its eye, so it needs far less than instinct suggests.
Start with a small pinch. If it is gone within a couple of minutes and the fish are still actively foraging, add a tiny bit more. If food drifts down and sits uneaten on the bottom, you have given too much. Over a few feeds you will learn the right amount for your tank.
Underfeeding is almost never the problem in a stocked community tank; overfeeding almost always is. Healthy fish are opportunists that always look hungry, so do not read begging as need.
How often to feed
Most adult community fish do well on one or two small feeds a day. Two small feeds suit busy, active fish slightly better than one large one, but once a day is perfectly fine, and a small daily amount beats a big occasional dump every time.
Adjust for the fish you keep:
- Small, fast-metabolism fish (nano fish, small tetras) do better with small amounts more often.
- Fry need feeding several times a day, in tiny amounts, as they have almost no reserves.
- Large or sedentary fish need less than you think, and many adults are fine fed every second day.
Feed at a consistent time so the fish learn the routine, watch them eat, and only top up if the first feed vanishes quickly. Newly added fish often will not eat for a day or two while they settle in; do not pile in food they ignore, as it only pollutes the water at the worst moment.
Types of fish food
No single food suits every fish. Build the diet around a quality daily staple, then add variety. Open each type to see when to use it.
Dry staples: flakes, pellets, granules
The everyday base of most diets: flakes for surface and mid-water fish, and sinking pellets, granules, or wafers for everyone else. A good-quality staple (Hikari, New Life Spectrum, Tetra, API, or Aqua One) is nutritionally complete and convenient, and insect-based options like Fluval Bug Bites are a solid modern choice.
Buy a pellet size your fish can actually swallow, and buy small tubs you will finish within a few months. The vitamins in fish food degrade once the container is opened, and flakes in particular go stale, so a huge tub is false economy.
Frozen foods
Frozen bloodworms, brine shrimp, daphnia, and mysis are protein-rich treats that most fish relish, and they are excellent for bringing out colour and conditioning fish for breeding. Sold in blister packs; thaw a cube in a little tank water and feed only a small amount.
These are a treat, not a staple. They are very rich, so feed them a couple of times a week rather than daily. Daphnia has the bonus of gently helping with constipation.
Freeze-dried foods
The same foods (bloodworms, brine shrimp, tubifex) dried into shelf-stable cubes. Convenient and long-lasting, they give you the variety of frozen food without needing freezer space.
Pre-soak them in a little tank water before feeding, because dry pieces can swell inside a fish and cause bloating. Like frozen food, a treat rather than a staple.
Live foods
Live brine shrimp, daphnia, blackworms, and microworms trigger natural hunting behaviour and are the gold standard for conditioning breeders and tempting fussy or newly imported fish to eat. Live blackworms are widely sold in Australia and a long-time favourite.
The catch is that live food can introduce disease or pests, so buy from a clean, reputable source and rinse it well. A treat and a breeding tool, not a daily requirement.
Vegetables and algae wafers
Herbivores and grazers need plant matter, not just protein. Algae wafers and sinking tablets feed bottom dwellers such as bristlenose plecos and otocinclus, and blanched vegetables (zucchini, cucumber, spinach, shelled peas) are a cheap and excellent supplement.
Blanch vegetables briefly so they sink, weigh them down with a fork or veg clip, and remove any uneaten pieces after a day so they do not foul the water. Remember that a bristlenose pleco also needs driftwood to rasp on for its digestion.
Whatever you feed, it has to reach the fish it is meant for. A tank fed only floating flakes leaves its bottom dwellers hungry. Match the food's form to where each fish feeds:
| Where they feed | Typical fish | What to give |
|---|---|---|
| Surface | Bettas, gouramis, hatchetfish, guppies | Floating flakes or floating pellets |
| Mid-water | Tetras, rasboras, danios, barbs | Slow-sinking granules or micro pellets |
| Bottom | Corydoras, loaches, plecos | Sinking pellets, wafers, and tablets |
| Grazers and herbivores | Bristlenose pleco, otocinclus, shrimp | Algae wafers and blanched vegetables |
Overfeeding: the number one mistake
If there is one habit to break, it is this one. Overfeeding is the most common beginner mistake, and the reason is simple: fish always look hungry, so people keep feeding. But a fish that begs is not a fish that needs more food.
What overfeeding actually does:
- Pollutes the water. Uneaten food decays into ammonia, which is toxic, then into nitrate, which climbs between water changes.
- Feeds algae. That surplus nitrate and phosphate is exactly what an algae bloom needs.
- Clouds the water. A sudden bacterial bloom (milky water) often follows a few days of heavy feeding.
- Harms the fish directly. Constant overfeeding causes constipation, bloating, and fatty organ damage over time.
The signs are easy to spot once you look: food sitting on the substrate after a feed, water that turns cloudy within days, nitrate creeping up between water changes, and algae you cannot get on top of. None of these come from underfeeding. The fix is the cheapest in the hobby: cut back to the 2 to 3 minute amount, skip a day if needed, and siphon out any food already on the bottom.
Fasting and digestion
A planned fasting day, one day a week with no food at all, is good for fish. It lets their digestive system clear, cuts the waste load, and does no harm whatsoever. It is standard practice among experienced keepers, not neglect. Most healthy adult fish can go a week or more without food, which is exactly why short absences are nothing to worry about.
Fry and very small fish are the exception: they have little in reserve and should not be fasted.
Fasting also fixes the most common digestive trouble. A fish that is bloated, struggling to stay level, or clearly constipated (often from too much dry food) usually improves after a 2 to 3 day fast, followed by a deshelled, boiled pea, which acts as gentle fibre. If it does not improve, look further in the diseases guide. Do not, however, use fasting to routinely paper over overfeeding; fix the daily portion instead.
Feeding while you are away
This worries new keepers more than it should. A healthy, established community tank is fine for up to a week with no feeding at all. Fish do not graze constantly in the wild, and a short fast is far safer than a sitter who overfeeds. For a weekend, or even a week, the best plan is usually to feed normally beforehand and simply not feed while you are gone.
For longer trips, there are two reliable options:
- An automatic feeder dispenses a measured dose on a timer and is dependable for two weeks or more. Set it up and test it for a few days before you leave, so you trust the portion size.
- A fish-sitter, but pre-portion each daily feed into a labelled container or a pill organiser so they physically cannot overfeed. A vague "just a pinch a day" instruction almost always ends in an overfed, cloudy tank.
Fry, nano fish, and heavily stocked or brand-new tanks have less margin and need arrangements sooner. Before any trip, do a water change and check the heater and filter, so the tank starts from a stable, clean baseline.
Australian notes
Food is easy to find. Australian aquarium shops and the big chains (Petbarn, Petstock) stock the major brands, Hikari, New Life Spectrum, Tetra, API, and Aqua One, along with frozen foods and Repashy gel premixes. Live blackworms are widely sold here and make an excellent conditioning food.
Appetite follows the seasons. Australian tanks swing with the weather more than heated-year-round setups elsewhere, and fish are cold-blooded, so their metabolism and appetite rise in warm weather and fall when it is cold. In a hot summer your fish may want a little more; in winter, and especially in unheated coldwater or goldfish tanks, they eat much less and should be fed less to match. Feeding a cold fish a full summer ration just leaves uneaten food rotting on the bottom.
The principle throughout: follow the fish, not the calendar. Feed to what they actually clear in a few minutes, and adjust down whenever they slow down.
Feeding ties into everything else: see why overfeeding drives algae, how water changes remove the waste it creates, and what the resulting numbers mean in the water parameters guide. For what each species needs, browse the species directory.