How to Tell if Your Betta Is Unwell

How to Tell if Your Betta Is Unwell

Bettas are good at hiding things. They are also small, and by the time a betta looks obviously wrong it has usually been unwell for days. The trick is not diagnosis. It is noticing the change early enough to do something simple about it.

This guide is about recognition: what to look at, what the usual causes are, and what to do in the first hour. It is not a substitute for a vet, and we cannot tell you what is wrong with your fish from a description.

Know What Normal Looks Like For Your Fish

There is no table of symptoms that works on every betta, because the only useful baseline is your specific fish. Spend two weeks paying attention before you worry:

• How it normally swims. Bettas are usually at the front, moving between the surface and the filter. A fish that used to patrol and now sits in one corner has changed.
• What its colour looks like when it is healthy. Some bettas are permanently muted, some shift noticeably with mood and lighting. You cannot spot a dulling fish if you never noticed the shine.
• How readily it eats. Bettas are not food-motivated the way a dog is, but a healthy one usually notices food within a second or two.

One caveat, and it matters: a young betta’s colour genuinely deepens as it matures, and fins keep filling out. That is development, not illness. Our guide to why young bettas change colour covers what is expected, and what is worth worrying about.

The Early Signs Worth Acting On

These are the ones that show up before anything looks dramatic:

• Clamped fins. The fins are held tight against the body instead of fanned. This is the single most reliable early sign there is, and it is easy to miss on a dark fish.
• Losing interest in food. Not refusing one pellet. Ignoring food that was previously instant.
• Hiding constantly. Spending the day wedged behind the filter or in a plant, when it used to come out.
• Colour going flat. A fish that has already coloured up losing its intensity is a health question. A young fish getting brighter is not.
• Sitting on the substrate. Resting on the bottom rather than moving through the water, especially with rapid gill movement.
• Any new mark. A spot, a patch of missing colour, a sore, or a frayed fin edge that was not there last week.

What Each One Usually Points To

This is a starting point, not a diagnosis. Several of these look similar in early stages, and more than one can be present at once.

White spot (ich)

Pinhead white dots, like fine salt grains, scattered over the body and fins. The dots are the parasite, not the disease, and there is often flicking or rubbing against hardscape early on before the spots show.

Fin rot

Fins look ragged, frayed, or shortened at the edge, and the fin membrane retreats between the rays. It is most often a water-quality problem wearing a symptom.

Velvet

A fine dusty gold or rust sheen over the body, visible most easily when the fish turns into the light. Heavy scratching is common. It is extremely contagious — it spreads through the water, through plants and decor, and through shared nets and buckets — and it can move through a whole tank in days. It is also easily mistaken for a dull or off-colour fish in its early stages, which is why photos in good light are worth taking before you start treating.

Cloudy eye

One or both eyes losing clarity, looking milky or fogged. Often follows a fight or a bump, and it can also come with a water quality problem.

Bloat or constipation

A swollen belly, often with a scale pattern that looks stretched. Nearly always linked to overfeeding, and frequently a side effect of a poor diet rather than a disease in its own right.

Popped scales and bloating

Raised scales, a pinecone texture, and a fish that looks larger than it should. This combination is serious and does not wait. See the section on asking for help below.

What To Do In The First Hour

Whatever the symptom, the first moves are the same, and they are deliberately conservative:

• Isolate the fish. A bare quarantine tank with a sponge filter, a heater, and nothing else. This applies even to a fish that lives alone, because a separate tank is where you can control temperature and treatment without disturbing the main setup.
• Take photos before you change anything. In good light, from the side and from above. This is genuinely useful, and it is the single most helpful thing you can do before asking anyone for advice.
• Test the water in the main tank. Ammonia, nitrite, and nitrate. Not the quarantine tank. You are trying to find out what the fish was living in.
• Do not start dosing. Several treatments interact badly, and treating for the wrong thing can make a mild problem serious. Salt-based remedies and temperature changes are not interchangeable.

A bare quarantine tank is worth keeping assembled even when nothing is wrong. It is the difference between reacting in ten minutes and reacting on Monday.

Treating It

What follows is the short version of what we would do, and the same protocol we use on our own care cards. It is a starting point, not a substitute for a product label or a vet, and it assumes you have already isolated the fish.

One rule covers all of it: dissolve any salt in a separate container of tank water first, then add it to the tank. Never pour dry salt straight in or onto the fish — undissolved salt burns fins and skin. And add it gradually over about an hour, in two or three goes, never all at once. Salt dumped in at once causes an osmotic shock that is worse than the problem you were treating.

White spot (ich)

• Aquarium salt, 1 level tablespoon per 10 litres. Dissolve first, add over about an hour.
• Raise the temperature slowly to 28-29°C. Slowly is the operative word. Do not jump the thermostat.
• Change the carbon media. Replace it, then add the new media back gradually so the filter is not stripped bare all at once.

Fin rot

• Fix the water first. Improve filtration and do daily partial water changes. Fin rot is usually a water-quality problem wearing a symptom.
• Support the fish with aquarium salt, dissolved first and added gradually as above.
• Reach for an antibacterial remedy only if the damage is genuinely spreading after the water is under control.

Velvet

• Treat the tank, not just the fish. This is the one that behaves differently from everything else on this page. Velvet’s free-swimming stage lives in the water, so moving a fish to a bare quarantine tank does nothing useful — you would be cleaning the fish and leaving the parasite where it is. Isolate a heavily affected fish for comfort, but the treatment has to go into the tank it came from.
• Use a copper-based medicine, dosed exactly per the label. Do not reach for salt. Salt treats white spot; it does not clear velvet, and following the white spot protocol is the most common reason velvet gets “treated” for weeks and comes back.
• Remove activated carbon before you dose. Carbon strips copper back out of the water, which makes the treatment useless. Put it back after the course is finished, where it then helps clear the residue.
• Keep the tank dark. Velvet is a photosynthetic dinoflagellate — it gets part of its energy from light, which is why dimming the tank genuinely helps rather than just calming the fish.
• Move any snails or shrimp out first. Copper is very effective against the parasite and lethal to invertebrates. It is also hard to fully remove from substrate and decor, so anything you want to keep alive should not go back in.
• Expect the full course, not just the visible improvement. Run it for the full term on the label even once the dusting looks gone, and expect a couple of days of the fish looking worse before it looks better.

Cloudy or bulging eye

Usually follows a fight or a bump, but it can also be a water-quality problem. Check the water before treating the eye. Supportive care is the same gradual aquarium salt as above, and keep the tank calm and heavily filtered.

Bloat or constipation

• Epsom salt, one pinch per 2.5 litres. It draws fluid out by osmosis, which is why it is the right salt here. Dissolve first, then add over about an hour.
• Fast a bloated fish. Keep the tank still and do not over-feed while it works. Then offer a shelled pea or live daphnia.

Popped scales and bloating

Raised scales with a pinecone texture, usually with a swollen belly, is the one on this list we will not give you a home protocol for. Do a partial water change, keep the tank still, and contact us or a vet with photos straight away. Do not add salt or start a treatment on your own.

Water Is Usually the Cause

Most betta illness traces back to one of three things: bad water, cold shock, or poor diet. That is worth repeating because it is the most useful thing in this article, and it is the part people skip.

• Keep the water between 24 and 27°C, and keep it stable. A steady 25 is safer than swinging between 24 and 28 twice a day. A heater with a working thermostat is not optional in a climate like ours.
• Ammonia and nitrite should both read zero. Always. If either registers, the filter is not cycled or is overloaded. Do a partial water change and test again the next day. Do not add fish to a tank showing ammonia.
• Nitrate should stay low. Weekly partial water changes do more than any product.
• A minimum of 20 litres, with 30 the sweet spot. Small containers make ammonia spikes and temperature swings dangerous, and there is no margin for error in a small tank.

Our Learn guide covers the water parameters and tank setup in full.

When To Ask For Help

Send us a message with photos if any of these are true:

• The fish has not eaten for more than two days.
• It is gasping at the surface or sitting on the substrate with rapid gill movement.
• Its scales are raised, or its belly is swollen and hard.
• You see an open sore, or the fins are visibly decaying.
• You are not sure, and you cannot tell whether it is the same fish.

That last one is the most common reason people ask, and it is a perfectly good reason. Early help is a lot easier than late help.

What We Can And Cannot Do

We will look at photos, talk through the water, and tell you what we would check next. We sell the equipment that makes keeping a betta straightforward, and we will happily talk you through a tank that is set up properly.

We cannot diagnose a fish, we cannot prescribe, and we will not tell you a product will fix something we have not seen. If a betta is genuinely in trouble, a vet with aquatic experience is the right call, and that is not a cop-out. It is what we would tell a friend.

Getting a healthy betta in the first place is most of the battle: choosing a fish that suits the tank you have, giving it the water and space it needs, and then actually looking at it every day.