Betta fin rot causes can be traced to any one of a range of bacteria or fungus. And where do those come from? Dirty Water!

Clean water is the single most important factor in keeping your betta fish healthy.

Interestingly, many diseases in both humans and animals can be linked back to poor hygiene. Cleanliness and fresh food is often more important than any medicine!

When the cause of fin rot is a fungus, it produces a whiteness on your Betta’s fins and rots the tail in a more even pattern.

A bacterial infection causes the tail to rot in a more ragged manner.

Fin rot is most prevalent among fish kept in unfiltered tanks or bowls. The reason is that your pet is being forced to swim in water that is contaminated by its own feces which is essentially ammonia.

This disease rarely infects healthy fish living in good conditions, but weak immune system and poorly kept aquariums are not the only causes of tail and fin root.

It can for instance be caused by injuries and other fish nipping the fins or just generally bullying them;
all this weakens the fish, puts it under stress and leaves it much more susceptible to tail and fin rot. This means that it isn’t very hard to prevent or at least minimize the risk of tail or fin rot in your aquarium.

All you have to do is to keep the aquarium clean, the fish healthy and well fed, and only combine fish that get along well. It is important to determine the cause of the disease when treating it and rectify the problem. Otherwise the disease might return within a short time.

Here are the main causes of betta fin rot:elevated nitrate and/or nitrite levels (The ammonia and nitrite levels should be at 0 ppm [parts per million] and nitrate should be under 20 ppm, maximum.)fluctuating water temperaturesfluctuating water pH levelsfin-nipping by tankmatesinjury of a fin in a water that isn’t clean enough to avoid infection of the injured fin

Poor diet exposure to toxins. Keeping your betta too cold and/or overfeeding your fish (extra food causes growth of bacteria that commonly causes fin rot).

Fin rot often only manifests itself in one or two fish at once and it is not particularly contagious, adding more weight to the theory that a weakened immune system is required for the disease to take hold.