Fin Rot

Symptoms

Early recognition is the key to a good outcome, so inspect your fish daily at feeding time. Ragged, frayed or receding fins, white or red edges, milky patches, and in advanced cases erosion into the body. If you notice several of these signs together, act promptly rather than waiting.

Causes

Opportunistic bacteria taking hold after fin damage, nipping, stress or — most commonly — poor water quality and high ammonia/nitrite. In almost all cases the underlying trigger is stress, poor water quality or the introduction of an infected fish, all of which weaken a fish's natural defences.

Treatment

First correct water quality with large water changes. Treat with an antibacterial medication (e.g. containing kanamycin or a broad-spectrum aquarium antibacterial). Aquarium salt can support mild cases.

Throughout treatment, increase aeration, remove activated carbon from the filter (it absorbs medication), complete the full course even after symptoms fade, and keep the water immaculate with regular changes. Always follow the medication's dosing instructions and dose for the tank's true water volume.

Prevention

Maintain pristine water, avoid overcrowding and fin-nipping tankmates, and feed a balanced diet to support immunity. The golden rules are simple: quarantine every new fish for 2-4 weeks, never overstock or overfeed, avoid sudden temperature or chemistry swings, and perform regular partial water changes. A stable, clean, low-stress aquarium prevents the overwhelming majority of disease outbreaks.

FAQ

This information is general guidance, not veterinary advice. Consult an aquatic vet for serious cases.