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Diseases of Betta splendens and proper treatment

All pictures were provided by Laura M. Schlögl.

Siamese Fighting Fish, picture 1 Siamese Fighting Fish, picture 2 Siamese Fighting Fish, picture 3 Siamese Fighting Fish, picture 4 Siamese Fighting Fish, picture 5 Siamese Fighting Fish, picture 6

Brief Description

This page covers common diseases of Bettas, explains reasons and also contains ideas on treatment. If you cannot find answer on your question, feel free to use a form at the bottom of this page to ask us directly! Sharing experiences and tips on curing sick Bettas is welcome too!

Betta splendens is a strong fish, and if kept in good condition, it won’t get sick. No matter what the disease is, when you notice a behaviour change, or some symptoms, remove the betta from other fish to avoid contagions.

Remember also to have an “aid kit” always ready:

  • A small tank for quarantine
  • A water heater
  • A small filter or water oxygenator
  • A dedicated net
  • Products like malachite green and methylene blue

There are a lot of diseases that can develop in aquarium, betta splendens usually are subjected to these:

  • Injuries
  • Swim Bladder diseases
  • White spot diseases
  • Ammonia poisoning
  • Fins and tail rot


Even if relations in aquarium looks good, sometimes injuries may happen. Often it’s impossible to understand how a fish has been injured; for bettas most of times it’s because of a male attack towards a female or vice versa, or an attack from a stronger fish disturbed by the betta male.

Bettas’ fins and tails are the most attacked by other fish, usually this is not a big problem and fins will grow again fast. Divide the betta in case it can’t swim properly; put it in the quarantine tank with same water parameters and add a drop of water disinfectant (methylene blue) to avoid infections; keep the fish well fed until the fins are a bit grown then you can move it again to the original aquarium.

Betta males can also get their fins damaged against an aquarium decoration, in this case remove the decoration, and leave the fish if it can still swim easily.

Injuries to the body can be more serious. Put the fish in the quarantine tank with really clean water, and directly clean the injury with a disinfectant like diluted Mercurochrome. do this treatment once a day, for 3 or 4 days, doing also massive water changes.

Swim bladder diseases

Swim bladder problems often belongs to other problem, like bacterial infestation, parasitic infestation, or constipation. Anyway betta splendens bladder is really delicate, and often when fish is old it can degenerate. If you are sure that there aren’t other problems that can be solved, just be sure that the fish can reach easily the water surface, in case it doesn’t, house it in a shallow water aquarium.

White spot diseases

Also called Ich (Ichthyophthirius).

This is the most frequent problem that can develop in an aquarium, it can be solved easily as long as your treatment is fast. Symptoms are white spots on body and fins, accelerate breathing, loss of appetite.

Ich first attacks the fish body and gills, covering it with white spots, after a few days the parasite falls on the aquarium ground where it increases in number and attacks other fish.

Divide sick fish and cure them apart. Anyway it’s better to do a light treatment also in the community aquarium even if fish look fine.

Firstly, set a higher temperature for three or four weeks (80°-82° F) and add some drops of malachite green into both aquariums. Higher temperatures help to reduce life span of Ich on the ground, reducing so the number of attacks and affected fishes.

Ammonia poisoning

This poisoning can kill fishes, but can also be solved fast. It depends on a bad balance in aquarium, maybe a high number of fish compared to plants, overfeeding, not working filter, few water changes and more. Control your aquarium and you will be able to understand what is the problem and solve it. Anyway you also need a fast solution, make huge water change (also the 50% of water) for 3 or 4 days and add activated carbon into the filter for about 5 days.

Symptoms are loss of appetite, fast breathing, lethargic movements, dirt water; to be sure of the diagnosis take a water test of Nitrite and Nitrate.

Fins and tail rot

If water conditions aren’t good a bacterial attack can develop a simple injury of fins in fins rot. Symptoms are: disintegrated fins, exposed fin rays, bloody and reddened base of fins.

Put the fish in the quarantine tank and cure it with antibiotic, and clean the injuries; use a light acid water (PH 6) that helps healing fast. Clean also the aquarium with water changes and methylene blue, then use active coal.

In shops you are able to find the medicaments thought for various diseases. Anyway you can solve some situations with chemical or house remedy:

  • Methylene Blue: is a disinfectant used for preventive cure, or to cure flukes, fungus, protozoic attack.
  • Malachite Green: is used for white spot disease and other bacterial attacks.
  • Salt bath: is great for light skin problems, like fungus. Put the fish for 15-30 minutes in a tank with half teaspoon of salt per gallon of water.
  • Formalin: can be used for external parasites. Put the fish for 30 minutes in a tank with 1-4ml of formalin per 3 gallons.
  • Garlic: for intestinal diseases you can add small pieces of garlic to fish food for some days. Garlic is a natural antibacterial. Of course remember to change water more often during this period.

Remember to do water changes once the treatment ends, and add activated carbon specially if you have plants inside the aquarium. Don’t add or remove activated carbon during the treatment! Before treating take off the aquarium snails and other invertebrates.

Remember always to put new fish into the quarantine tank even if they look healthy; leave them there for 20 days and check their effective status. Fish from shops can develop diseases that can kill your fish. Moreover, chemical cures kills filter bacteria and may reasult in weak plants, so it’s better to cure fish in the quarantine tank.

To prevent diseases, it is important to verify the correct working of the biological filter. Do not exceed the food quantity, have enough plants and remove died fish or died plants as soon as possible died. You have also to remember to check that the number of fish is well proportioned to the water amount: it is normal to desire a populated aquarium, but a high population is one of the first causes of the epidemic.

Copyright note: This article is originally written by Michela Ferretti. owns the full copyright of this article.

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