Best fish food for a community tank: how to work it out

Why "the best food" is the wrong question

Search for the best fish food for a community tank and you'll mostly find ranked lists of tubs. The trouble is that a community tank isn't one animal. It's several species that evolved in different places, feed at different depths, have differently shaped mouths and digest different things. A food that suits your tetras perfectly can float straight past your corydoras and do almost nothing for your otocinclus.

So this guide doesn't rank products. It gives you the questions to ask, in order, so you can build a feeding plan around the fish you actually keep. Once you've done it, you'll know what job each tub in the shop is supposed to do.

Step 1: map who eats where

Write down every species in the tank. Next to each one, note where it takes its food:

• Surface: fish that patrol the top and snap up anything floating. Most livebearers (guppies, platies, mollies) and hatchetfish feed here.
• Mid-water: fish that take food as it drifts down through the water. Most tetras, rasboras and danios.
• Bottom: fish that sift, graze or pick at the substrate and hard surfaces. Corydoras, loaches, plecos and otocinclus.
• Night or dusk: some bottom dwellers, such as kuhli loaches and many plecos, do most of their feeding after the lights go off.

Base this on what you see in your tank, not just on care sheets. Plenty of mid-water fish will happily rise to the surface at feeding time. What you're really looking for are the fish that can't or won't come up, because a single floating food leaves them out. Still planning? Run the list through the stocking calculator first.

Step 2: look at mouths

A fish's mouth tells you a lot about where it feeds and what size of food it can manage.

• Upturned (superior) mouth: opens upwards, built for taking food at the surface. Guppies and hatchetfish are classic examples.
• Terminal mouth: at the front of the head, pointing forwards. Typical of mid-water fish such as most tetras, which pick food out of the water column.
• Sub-terminal (inferior) mouth: on the underside of the head, often with barbels. Built for the bottom. Corydoras and loaches are the familiar ones.
• Sucker mouth: a specialised underside mouth for rasping and gripping surfaces. Plecos and otocinclus.

Then think about size. A neon tetra's mouth is tiny, and a flake or pellet sized for larger fish may simply be too big. It gets spat out and drifts to the bottom to rot. If your smallest fish keep rejecting food, suspect particle size first. Crushing flake between your fingers, choosing micro pellets, or using small frozen foods such as baby brine shrimp or cyclops all help.

Step 3: work out what each fish is built to eat

This is the step most feeding advice skips, and it matters most over the long term. Look up each species' natural diet and put it in one of these broad groups. Many fish sit between two, but they're a useful starting point.

Carnivores and insectivores

Fish that mostly eat small animals in the wild: insect larvae, tiny crustaceans, worms. Many small tetras and rasboras are micropredators like this, though most also pick at some plant matter, and bettas lean firmly this way. They do best on foods built around animal protein.

Omnivores

Fish that eat both animal and plant material. Platies and mollies graze algae as well as taking small invertebrates. Corydoras forage the substrate for worms, larvae and whatever else they can find. Omnivores are the easiest group to feed, but easy doesn't mean the same meaty food every day is ideal.

Herbivores and aufwuchs grazers

Fish that spend much of the day grazing algae and biofilm. Aufwuchs is the German word keepers use for that whole film of algae, microorganisms and debris on rocks, wood, glass and leaves. Otocinclus are the obvious community example. They need a steady supply of plant-based food and won't thrive on whatever happens to fall to the bottom.

Wood-eaters

A few plecos, notably Panaque and Panaqolus species, rasp and swallow a lot of wood. How much nutrition they get from the wood itself is still debated, but keepers generally agree they need driftwood alongside vegetable foods. Bristlenose plecos (Ancistrus) rasp wood too.

Why a mismatch causes problems

A fish's digestive system is adapted to its natural diet. Grazers tend to have long guts suited to breaking down plant material slowly; carnivores tend to have shorter ones. Feed a grazer a rich, high-protein diet day after day and you risk digestive trouble and poor condition. In some herbivorous African cichlids, high-protein diets are widely linked to the condition keepers call bloat. Go the other way and feed a carnivore mainly plant-based food, and it can't make good use of it: more passes through as waste and the fish may slowly lose condition.

In a community tank, the usual risk is the first one. The meaty foods the mid-water fish love end up being what the grazers eat too, simply because nothing else reaches them.

Step 4: pick formats that reach each level

Now choose formats that put the right food in the right place. Each has a job and a downside.

• Flakes: float, then sink slowly, so they suit surface and mid-water fish and are easy to crumble for small mouths. Downside: thin flakes lose vitamins faster than denser foods once the tub is open, and in a busy tank very little reaches the bottom.
• Micro pellets and granules: small, dense particles. Some float and some sink slowly, so check the packaging. Easier to portion than flake. Downside: pick a grade too large and the smallest fish can't manage it, and dry pellets swell once wet.
• Sinking pellets, tablets and wafers: get food down to where corydoras, loaches and plecos feed. Algae or vegetable-based wafers suit grazers. Downside: anything not eaten sits on the bottom and breaks down, so a wafer the tank didn't need becomes a water quality problem overnight.
• Gel foods: a powder mixed with hot water that sets into a soft block you can cut up or press onto a rock. Useful for grazers and slow bottom feeders because it holds together in the water for a while. Downside: more effort to prepare, and once made it needs storing as the maker directs.
• Frozen foods: bloodworm, brine shrimp, daphnia, cyclops, mysis. Close to natural prey and very appetising, which makes them good for fussy or newly arrived fish. Downside: they need thawing and portioning with care (see defrosting frozen food), and the packing liquid adds organic load.
• Live foods: the strongest feeding response of all, useful for conditioning or tempting shy fish. Downside: the hygiene risk depends heavily on the source, and live food that dies uneaten rots fast. The live foods guide covers which are safest.
• Blanched vegetables: courgette, cucumber or spinach, softened in boiling water and weighted down. Essential for grazers and enjoyed by many omnivores. Downside: remove what's left within about a day, before it breaks down. Shelled peas are better as an occasional item than a staple.

Step 5: solve the competition problem

This is where most community tanks quietly go wrong. Food goes in, the fast surface and mid-water fish swarm it, and within seconds it's gone. The fish at the top look well fed, so you assume everyone is, while the corydoras pick at crumbs and the otocinclus get nothing.

So do bottom feeders get enough food? Only if you deliberately make sure they do. Tactics that work:

• Feed at two points: drop the surface food at one end. While the top fish are busy there, add sinking food at the other end.
• Feed the top first: a small amount of floating food occupies the fast eaters, then add the sinking food a minute later.
• Feed after lights out: for nocturnal and dusk-active species, add sinking food shortly after the main lights go off. The daytime fish settle and the bottom dwellers get a clear run. Check in the morning and remove leftovers.
• Target feed: use a length of rigid tubing, a pipette or a turkey baster to place food on the substrate near where your bottom fish rest, or weight vegetables where grazers like to sit.
• Watch bellies, not the frenzy: a thin or concave belly on a corydoras or otocinclus while the tetras look round means food isn't reaching the bottom.

For more on keeping the bottom layer healthy, see the best bottom feeder fish and corydoras care.

Step 6: rotate foods and learn to read a label

Variety is the closest thing to a universal rule in fish feeding. No single prepared food is likely to be ideal for every fish in a mixed tank, and rotating spreads the risk: if one is short on something, another may make up for it. It also keeps fussy fish interested. A dry staple for each feeding level, plus frozen or vegetable feeds on some days, is plenty for most community tanks.

Reading an ingredient list

You don't need to be a nutritionist to get something useful from a label. Things worth looking at:

• The first few ingredients: ingredients are usually listed in descending order by weight, so the first three or four tell you what the food mostly is. For a carnivore or omnivore food, you'd generally hope to see an animal ingredient near the top. For a grazer food, algae or plant material should feature prominently.
• Named versus vague ingredients: a named ingredient (whole krill, insect meal, a named fish meal, spirulina) tells you more than a broad category such as "fish and fish derivatives" or "derivatives of vegetable origin". Broad categories aren't automatically bad, but they make it harder to know what you're feeding.
• Fillers and binders: dry foods need something to hold them together, often a starch such as wheat. That's normal. The question is whether a cheap starch sits at the very top of the list, ahead of everything else.
• Protein percentage: the label figure is crude protein, an estimate calculated from nitrogen content. It says nothing about how digestible or useful that protein is. Higher isn't automatically better, because a grazer doesn't need what a micropredator needs. The figure is also calculated on the food as sold, so frozen foods, which are mostly water, show much lower numbers than dry foods even when they're excellent food.

Use the label to check that a food fits the diet group from step 3, not to chase the biggest number.

Steps 7 and 8: freshness, amount and frequency

Freshness. A well-chosen flake that has been open on top of a warm tank for a year isn't the food it was when you bought it. Buy tubs small enough to finish, keep them sealed, cool and dry, and away from the tank itself. The guide to whether fish food expires covers how long each type lasts once opened and how to tell when it has gone off.

Amount and frequency. Having several foods for several levels makes overfeeding easier, not harder, because each one feels like only a small extra. Treat the tank's daily food as one budget and split it across formats. Portions, timing and fasting days are covered in detail in how much to feed fish, so they aren't repeated here.

A worked example: neons, platies, corydoras and otocinclus

Here's the method applied to a common peaceful setup: a group of neon tetras (Paracheirodon innesi), a few platies (Xiphophorus maculatus), a group of corydoras and a group of otocinclus, in a planted tank that has been running for a few months.

• Map: platies at the surface and upper water; neons in mid-water; corydoras on the bottom; otocinclus on glass, leaves and wood, grazing for much of the day.
• Mouths: platies have slightly upturned mouths and take floating food readily. Neons have very small terminal mouths, so particle size matters most for them. Corydoras have underslung mouths with barbels; otocinclus have sucker mouths.
• Diet: neons are small micropredators that also take some plant matter; platies are omnivores that graze algae; corydoras are omnivores that forage for small invertebrates; otocinclus are grazers that need plant-based food.
• Competition: platies and neons will strip floating food before much reaches the bottom. Corydoras can hold their own on sinking pellets, but otocinclus are slow, timid eaters and the most likely to lose out.

What that adds up to:

• A small-particle staple (crushed flake or micro pellets) for the upper and mid-water fish, ideally one with some plant content for the platies.
• A sinking pellet or tablet for the corydoras, dropped at the far end once the top fish are busy, or shortly after lights out.
• Blanched vegetables and an algae-based wafer or gel food for the otocinclus, placed where they graze, with the tank's own algae and biofilm doing a lot of the work. The otocinclus care guide explains why a mature tank matters so much for them.
• Small frozen foods a couple of times a week: baby brine shrimp, cyclops or daphnia suit the neons' mouths, and whatever sinks reaches the corydoras.

Sample weekly rotation

Day	Top and mid-water	Bottom and grazers
Mon	Small-particle dry staple	Sinking pellets or tablets
Tue	Small frozen food, thawed	Blanched vegetable for the grazers
Wed	Dry staple with plant content	Algae wafer or gel food after lights out
Thu	Small-particle dry staple	Sinking pellets or tablets
Fri	Small frozen food, thawed	Blanched vegetable for the grazers
Sat	Dry staple with plant content	Algae wafer or gel food after lights out
Sun	Fast day or a very light feed	Grazers work on the tank's own algae

Treat this as a template, not a prescription. If the corydoras look thin, shift more of the daily budget to the bottom; if the otocinclus look well rounded and are still grazing the glass, they may need less extra.