A bacterial infection may cause this tail fin and mouth rot in susceptible fish, especially in those fish who are bullied or injured by fin-nipping tank mates. This is often caused by poor water conditions.
- A progressive deterioration of the tail and/or fins
- Fins become frayed or their color may fade
First test the aquarium water to review overall water quality and conduct a partial water change to ensure healthy conditions. If the clamped fins are the result of infections, a multipurpose fungus treatment like protozin is the first line of treatment. Good practice of adding 1 tbs. aquarium salt per gallon will help prevent clamped fins.
It is always strongly advised that water conditions are tested to ensure they are at the correct parameters for the fish you are keeping so regular testing and regular water changes should prevent your fish from contracting tail, fin and mouth rot fish disease.
Tropical Fish Site takes no responsibility for diagnosing the exact problem with your tropical fish, this is purely meant as a guide only. Be sure to look at other common tropical fish diseases to ensure you have made the correct diagnosis as there is often crossover between them.