Signs Your Betta Fish Is Sick

Find out how to tell if your betta is ill and what you might be able to do about it.

Written by
betta fish
Lethargy could be a sign of illness. choikh/Shutterstock

A healthy betta with bright colors and full flowing fins is one of the most alluring and elegant sights an aquarist can enjoy. They’re not difficult animals to care for, but because of the reputation they have acquired for being a good “first fish” due to their ability to thrive in minimalistic systems, they often wind up neglected and kept in tanks that are too small.

Just like any other fish, bettas are susceptible to bacterial, fungal and parasitic infections. Making regular observations of your betta’s behavior and taking note of any unusual changes can help you identify, diagnose and treat an illness before it becomes fatal. As always, water quality is of utmost importance, and clean water is the single most important thing you can give your betta. Think of it like air for you or your furry companions. Without clean air, your dog or cat would be unwell and could suffer from a wide variety of health problems. The same is true for fish with their water. Water that is clean, the right temperature and the right pH can make all the difference for your betta.

Disease prevention by way of clean water, enough living space and high quality food is, of course, the best method for keeping your betta healthy, but you might bring one home that is already ill. Here are some behaviors to watch out for that might indicate your betta isn’t feeling well:

  • Lethargy
  • Faded color
  • Refusing food
  • Damaged fins
  • Labored breathing

Common Betta Fish Diseases

If your betta exhibits one or more of these behaviors, be sure to pay close attention and carefully observe your fish to try to determine the root of the problem.


The most common disease I’ve seen afflict bettas is Columnaris, a Gram-negative bacterial infection that often manifests itself as cottony patches on the body and fins. The Columnaris bacterium (Flavobacterium columnare) is present in all water, but unless the fish is stressed by suboptimal conditions — such as poor water quality, an inadequate diet or shipping/handling — it likely won’t become infected. If you suspect Columnaris — often called Cotton Mouth, Mouth Rot or Saddleback — do a large water change and then treat with an antibiotic and anti-fungal regimen.


Popeye is another bacterial infection that results from prolonged exposure to poor water quality. The eyes appear to bulge out, and the treatment is water changes and dosing with an antibiotic, probably Maracyn.

Fin Rot

Fin rot is caused by the same thing, and the fins are red along the edges and recede as the tissue deteriorates. Again, water quality needs to be improved through large water changes, and treatment by way of an antibiotic such as Maracyn can stop the infection.

Hole In The Head

Hole in the Head disease looks like just that, holes in the head above the eyes, and generally results from poor water quality and nutrition. Changing the water, antibiotics (metronidazole) and switching to a more nutritious diet can sometimes cure this ailment.


Dropsy, also called Pineconing because the scales protrude out from the swollen body like the scales of a pinecone, can be caused by a virus, bacteria, or parasite. This makes it more difficult to treat since we can’t usually determine the exact cause. Consequently, it is best to cover all your bases and use a combination of broad-spectrum options such as KanaPlex and Maracyn.

Swim Bladder Disease

Swim bladder disease, or disorder, is not entirely uncommon either, but often times is the result of weak genetics, and there is no solution for a birth defect. It can also be caused by overfeeding and/or bacterial infection, so in an effort to consider all possibilities, fasting for two to three days combined with a water change and treatment with Maracyn would be a good course of action. It is easy to feed your betta too much since they’re so responsive to food, but underfeeding is always better than overfeeding.


Ich, short for Ichthyophthirius multifiliis, is commonly called white spot disease. It is a parasitic infection that looks as if granulated sugar has been sprinkled all over your fish. As you can imagine, this is extremely uncomfortable for your betta, so you might see them rubbing their bodies against objects to try to dislodge the parasites, a behavior called “flashing.” Ich can be treated with methylene blue or malachite green, so make sure to choose a medication that contains one of these. Transferring your betta to a hospital tank is also a good idea because it will keep your fish away from free-swimming parasites and give them the best, clean environment in which to recover.

The common thread with almost all these potential betta illnesses is water quality. As I mentioned earlier, the single best thing you can do for your betta, or any fish, is to give it the cleanest water possible. To keep your betta healthy and avoid disease, do regular water changes, condition your water or use RO water, feed it nutritious food, add a heater to keep the temperature above 75 degrees Fahrenheit, and make sure that it has a habitat of at least two gallons. I tend to think that simple live plants, such as java moss, are useful additions because they readily absorb the nitrogenous waste products of fish as they grow, keeping your water cleaner with less work.

Bettas are beautiful fish, and they can be a source of enjoyment for novices and experienced aquarists alike.

Article Categories:
Freshwater Fish