Fin Rot
Aquarium water is full of all kinds of organisms including bacteria. Healthy fish are not affected by this bacteria, but if your fish become stressed out or sick they could develop a disease called Fin Rot. Fin Rot is caused by the bacteria in the aquarium and basically rots away the fins of your fish. It starts by attacking a cut or weak spot in the fin and progress along until the whole fin is gone. Needless to say this can kill your fish!If you notice that your fishes stands are ragged looking or discolored and you could suspect that they have been wrought. Normally fish can fight off this bacteria but if you see it happening In your aquarium this probably means there is some kind of stress on the fish. This could mean that there is too much ammonia in the tank or your fish are not compatible and the more aggressive fish are attacking the more laid-back fish causing them stress as well as physical injury.
the best way to treat fin rot is to make sure that the water quality in your tank is optimum. well you should be doing periodic water changes to keep the water quality good it doesn’t hurt to also cast once a week to make sure that your levels of ammonia nitrite and nitrate are in check.
If you find that your fish have rotting fins tend to the water quality immediately. also keep an eye on the fish in the tank. His one fish getting picked on? Are there some things that see more aggressive in going after the other fish? When putting fish in the tank you need to make sure that they will all get along as not all species are compatible.
Keep a close eye in your aquarium in treating the cause of disease as soon as you see it will help keep your fish happy and healthy.