What do plecos eat? Herbivore vs carnivore plecos and how to feed them

Plecos do not live on algae and leftovers. That is the biggest myth in the hobby, and it starves a lot of plecos. What a pleco needs depends on its type: some are mainly plant eaters that need vegetables and driftwood, while others, such as the zebra pleco (L046) and its Hypancistrus relatives, are meat eaters that need protein.

So the first step is to find out exactly which pleco you have. The second is to feed it on purpose, usually at night, with food that reaches the bottom where it lives.

How to tell if feeding is going wrong

A sunken belly. Look at your pleco from below through the glass, or from the side when it is on the front pane. A well-fed pleco has a gently rounded belly. A hollow or concave belly means it is not getting enough.
A thin, bony look behind the head, with the body narrowing sharply.
Constant restless searching on the glass and gravel, even in daylight.
Chewed plants or a pleco rasping at soft wood until it's shredded, often a hungry herbivore.
Faded colour, slow growth, or a pleco hiding and never seen at the food.
Uneaten vegetables or gel food going cloudy and fuzzy: you are overfeeding, or feeding the wrong thing.

When it's a problem

Normal: a rounded belly, a pleco that comes out at lights-out to eat, food gone by morning.
Early: a slightly flat belly, or you never see it eat. Start targeted feeding now.
Serious: a clearly sunken belly and bony look. A pleco in this state can starve over a few weeks.
Emergency: a very thin pleco that has stopped eating altogether, or a pleco lying on its side. Check the water quality first; a starving fish is also weaker against disease. See fish dying.

What to do right now

Identify your pleco. Note the L-number if the shop gave you one, or compare photos. "Pleco" covers hundreds of species.
Sort it into a feeding group:
- Mainly plant eaters: bristlenose (Ancistrus). They also eat some protein.
- Wood eaters: royal plecos (Panaque) and clown plecos (Panaqolus). They need driftwood to rasp on all the time, plus vegetables.
- Omnivores: common and sailfin plecos and many others. Feed both vegetables and protein.
- Meat eaters: zebra pleco (L046) and other Hypancistrus, plus Leporacanthicus and Pseudacanthicus. They need protein: frozen bloodworm, brine shrimp, mysis, chopped shrimp, and quality carnivore pellets or gel foods.
Feed after the lights go out. Most plecos are night feeders and shy. Drop food near their cave or hiding place.
Use sinking food. Plecos almost never get flakes. Use sinking wafers, pellets or gel food.
Check in the morning. Was it eaten? Remove what's left.
Watch the belly over the next week. It should fill out within days.

What to do next

Vegetables (for plant eaters and omnivores)

Good choices: zucchini (courgette), cucumber, squash, blanched peas, and green beans. Cucumber is mostly water, so use it as a treat rather than a main meal.
Prepare them: wash well (or peel non-organic vegetables to reduce pesticide), cut a slice about 1 cm (half an inch) thick, then blanch it in boiling water for about 30–60 seconds, or microwave it briefly, so it softens and sinks.
Weigh it down with a vegetable clip, a stainless-steel fork, or a plant weight.
Remove it within 24 hours, sooner in warm tanks. Rotting vegetables foul the water quickly.

Wood (for Panaque, Panaqolus and bristlenose)

Keep aquarium-safe driftwood in the tank permanently. Wood-eating plecos rasp it constantly and their droppings become fine wood shavings.
Research by Donovan German found that these fish actually digest very little of the wood itself; they seem to get most of their nutrition from the softer material on it and from other foods. So wood is necessary, but it is not a whole diet: feed vegetables and prepared foods too.

Protein (for Hypancistrus and other carnivores)

Feed frozen bloodworm, brine shrimp, mysis or chopped prawn, plus a quality carnivore pellet or wafer. Zebra plecos especially like brine shrimp; in a 2019 feeding study, it was their first choice.
Zebra plecos have small mouths and are not grazers. They don't scrape algae, so an algae wafer alone will slowly starve them.
Keep zebra plecos warm (about 27–30 °C, 80–86 °F). Their appetite drops in cool water.
Keep them away from fast, greedy bottom feeders, such as big corydoras groups or loaches, which can eat their food first.

Gel foods

Gel foods are powders you mix with hot water to set into a jelly. They are excellent for plecos: they sink, hold together, and come in herbivore and carnivore types.
Don't leave gel food in too long. Feed a small piece, and remove what's left the next morning. Gel food that sits for days rots, clouds the water and can cause an ammonia spike; overfeeding gel food has killed whole tanks of plecos. See overfeeding.

Products that help

Sinking algae or spirulina wafers: a staple for bristlenose and other plant-eating plecos.
Sinking carnivore pellets or wafers: high-protein staple for zebra plecos and other meat eaters.
Gel food powder (herbivore and carnivore versions): a complete, sinking food you can make up in batches and freeze in cubes.
Frozen bloodworm, brine shrimp and mysis: protein for carnivores and a treat for omnivores.
Vegetable clip or stainless-steel weight: holds vegetables on the bottom.
Aquarium-safe driftwood: essential for wood-eating plecos, and good for most others.
Caves (one per pleco plus a spare): a pleco that feels safe comes out to eat.
Keep on hand: two or three suitable foods, so you can rotate them, and an ammonia test kit.

How to prevent it

Research before you buy. Ask the shop exactly which species it is and what it eats.
Never rely on algae. Even a tank full of algae won't feed a pleco for long, and many plecos don't eat algae at all.
Feed the pleco on purpose, every day or most days, at lights-out, near its cave.
Match the food to the fish. Plant eaters get mostly vegetables with some protein; meat eaters get mostly protein with the odd vegetable.
Remove leftovers every morning.
Check bellies weekly.
Feed the rest of the tank too, so other fish don't steal the pleco's food.

Why it happened

Plecos are sold as "algae eaters" or "tank cleaners", so many owners never feed them. They also hide by day and eat at night, so owners don't notice they are going hungry until the belly sinks. And because "pleco" covers both plant-eating and meat-eating species, the right food for one can be useless for another. Overfeeding the wrong food creates a second problem: rotting leftovers and dirty water.

When to get help

If the belly doesn't fill out within a week or two of good feeding, ask an experienced pleco keeper or a fish vet. Internal parasites or disease may be the real cause.
If the pleco is bloated rather than thin, see bloated fish.
Plecos and other bottom fish are often the first to suffer when ammonia rises. If yours stops eating after you've fed heavily, test the water; see ammonia.
For general feeding questions, see how often to feed fish.

In the game

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