Betta not eating: 8 common causes and what to do today

A betta that stops eating is usually cold, stressed by its water, newly moved, or overfed and constipated. Check the temperature first: bettas are tropical fish and need about 25–27°C (77–80°F), and a betta in a cool room often stops eating within days.

A healthy adult betta can go several days without food without lasting harm, so you have time to find the cause. But if it refuses food for more than about five days, or shows other signs such as clamped fins, swelling or lying on the bottom, treat it as a health problem.

How to identify it

First make sure your betta is really not eating:

Refusing: it ignores food completely, or takes pellets and spits them out again and again.
Missing food: it tries but misses. Bettas have short-range eyesight, and old or blind bettas struggle to find food.
Being beaten to it: tankmates grab the food first.
Already full: many bettas are overfed. A betta's stomach is roughly the size of its eye, so two or three small pellets is a meal.

Then look for clues to the cause:

Cold water: slow, sitting on the bottom or a leaf, pale.
Poor water: clamped fins, gasping at the surface, frayed fins.
Constipation: swollen belly, no droppings, sometimes a stringy white dropping.
Illness: white spots (ich), gold dust (velvet), ragged fins (fin rot), raised scales (dropsy) or trouble swimming (swim bladder).
Wrong food: new brand, pellets too big or too hard, or freeze-dried food it doesn't like.

When it's a problem

Normal: a new betta not eating for the first 2–3 days in a new tank. A betta skipping one meal. A male busy building a bubble nest eating less.

Early concern: 3–5 days of refusing food with no other signs. Check temperature, water and food.

Serious: more than about 5–7 days, or a betta getting visibly thinner (a hollow belly behind the head).

Emergency: not eating plus gasping, lying on its side, raised scales, a large swelling, or red patches. Act within hours.

What to do right now

Check the temperature with a thermometer, not by touch. If it's below 24°C (75°F), add or adjust a heater and raise it slowly, about 1°C (2°F) per hour, to 26°C (78°F).
Test the water for ammonia, nitrite and nitrate. If ammonia or nitrite is above zero, change 30–50% with dechlorinated water at the same temperature.
Remove any uneaten food so it doesn't foul the water.
Look at the belly. If it's swollen, fast for 2–3 days (see bloated fish).
Look for illness signs listed above, using a torch from the side.
Check for stressors: a strong filter current, a reflection it keeps flaring at, a busy room, a tankmate nipping it.

What to do next

A new betta (the adjustment period)

Moving is stressful. Many bettas don't eat for 1–3 days after coming home. Keep the lights dim, offer 1–2 pellets once a day, and remove anything not eaten after five minutes. Don't keep adding food "in case."

Cold water

Bettas are cold-blooded. In cool water their metabolism slows, they stop being hungry, and their immune system weakens. A small unheated bowl in a Canadian or northern US home is often 18–22°C (64–72°F), far too cold. Every betta tank needs an adjustable heater. One small study on betta fry found lower survival at 25°C than at 27–29°C. Expect appetite to return within a day or two of warming up.

Constipation

Overfeeding and dry, low-moisture foods are the usual causes. Fast for 2–3 days, then feed a little thawed daphnia, which acts as a natural laxative. Soak dry pellets in tank water for a few minutes before feeding so they swell before your betta eats them, not after. See bloated fish.

Illness

Loss of appetite is one of the first signs of many diseases. Fix the water and temperature first, then follow the guide for what you see. If you medicate, remove carbon from the filter and finish the full course. Move the betta to a hospital tank if it shares a tank with shrimp, snails or live plants, because many medicines harm them.

Pellet size and food type

Use small betta pellets. Large pellets meant for other fish get spat out.
Bettas are carnivores. Flakes made for community fish are often ignored.
Try a frozen food: bloodworms, brine shrimp, mysis or daphnia. Thaw a small piece in a cup of tank water first. Most bettas that refuse pellets will take frozen food.
Replace dry food every couple of months once opened. Stale food loses vitamins and some fish refuse it.
If you've changed brands, try the old food again, then mix in the new one slowly.

Feeding a picky or old betta

Drop food in the same spot each time, near where the betta rests. Feed with the light on, and use a turkey baster or tweezers to place frozen food in front of it. Feed once or twice a day, only what it eats in a couple of minutes.

Products that help

Adjustable aquarium heater: the most common fix for a betta that won't eat.
Aquarium thermometer: so you know the real temperature, not the heater dial.
Liquid test kit: rules water quality in or out.
Small betta pellets: sized for a betta's mouth.
Frozen bloodworms, brine shrimp or mysis: tempt fussy eaters.
Frozen daphnia: a gentle, fibre-rich food for constipation.
Sponge filter: filtration without the strong current that tires long-finned bettas.

Keep on hand: a spare heater, water conditioner and a small pack of frozen food.

How to prevent it

Keep your betta in a heated, filtered tank of at least 19 litres (5 gallons).
Hold the temperature steady at about 26°C (78°F).
Feed small amounts once or twice a day, with one fasting day a week.
Vary the diet between pellets and frozen foods.
Change 20–30% of the water weekly.
Avoid fast, nippy tankmates that steal food or stress your betta.

Why it happened

Appetite is one of the most sensitive signs of a fish's health. Cold water, dirty water, stress, a full gut and illness all turn it off. Most of the time the cause is the setup, not a disease, which is good news because it's easy to fix.

When to get help

Get help if your betta hasn't eaten for a week despite warm, clean water, if it is getting thin, or if it has swelling, raised scales, sores or trouble swimming. An aquatic vet or an experienced fish shop can help work out the cause.

In the game

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