Bacterial - Can be caused by a number of different bacteria
Fin rot is a bacterial disease that attacks the fins of freshwater fishes. It is a very treatable condition that often occurs as the result of a secondary infection. If fin rot is left untreated, it can be fatal to the infected fish.
White edges appearing on the fins
Frayed or otherwise rough looking fins
Inflamation of the base of the fins
In advanced cases, entire fins may rot off the fish
The first sign of infection is often ragged or frayed fins. You may also notice that the fins appear to be shorter than normal. The fin edges begin to look white and then the entire fin may become red and irritated. As the disease progresses, bloody areas and red inflamation become more evident. Secondary infections such as white fungal infections may occur at any time during the infection.
Determine the root cause of the infection: Fin rot does not normally affect healthy fish in a healthy environment. The most common cause of fin rot is poor water quality, but some other possible causes include improper feeding, tank overstocking, excess handling of fish or the presence of aggressive fish.
Water change: Unless you are 100% certain your water parameters are ideal, do a 30% water change every 3 days until the symptoms resolve.
Treat with antibiotics: Fin rot can be caused by any number of gram negative bacterial infections. Use any over the counter aquarium antibiotic that is effective against gram negative bacteria. Chloramphenical, Oxytetracycline, and Tetracycline are all acceptable treatments.
Addition of aquarium salt: Aquarium salt can helpheal the damaged tissue. Do not use aquarium salt if your aquarium has fish that are sensitive to it, such as catfish. Follow the instructions on the aquarium salt container.
Perform regular water changes to ensure good water quality.
Check your water parameters regularly with a testing kit.
Use only fresh food and feed the fish only as much food as they will consume in 30 seconds.
Do not overstock your aquarium, and watch for aggression. You can check your stocking level at Fish Tank Planner.