Velvet is the most common disease among Bettas. It is caused by an algae that feeds on the slime coat of the betta, as well as other bodily fluids. It attacks the gills first, then spreads over the rest of the body. Because of this, early detection is a must, for by the time it becomes very obvious the fish’s gills will be heavily infested.
Diagnosis: A betta with velvet will become lethargic and usually lay on the bottom of the tank. They clamp their fins and are not crazy about their food, like they should be. If a flashlight is shone on the fish, it will look like it has a dull, light-brown fuzz over it.
A Betta infected with VelvetCause: Iffy water quality and bad temperature changes, as well as other stressors, bring this on. It is actually caused by an algae, as I said before. It is highly contagious, and if Betta is in a community tank the whole tank should be treated. Clean water and stability is the best preventive measure.
Cure: Must be treated QUICKLY. It attacks the gills first, and is therefore in a serious stage at the point of detection. Copper-based medicines work well, but copper levels must be closely monitored. Maracide is easier to use and still quite effective. Malachite green will work, but that’s harsh stuff. I don’t usually reccomend it for things that afflict the gills because it’s a gill irritant itself. Aquarisol is effective, as well as, Acraflavin, but Acraflavin can sterilize bettas. Completely darkening the tank can kill the velvet slowly, as it is an algae and needs to metabolize light. This will only slowly starve it though, and should only be used to supplement medication.
If your betta has come down with velvet, quick treatment is crucial. Get some salt in the tank immediately (make sure it’s non-iodized and make VERY sure it does not contain Prussiac Acid. Aquarium salt is best) to slow the spread. Then go to the pet shop ASAP. It is a good idea to treat with an antibiotic to prevent secondary infections.