I got this fish from LFS 6 days ago. He is eating very well and behaving 'normal'. The spot on the back of his tail fin appeared 2 days ago. There are 5 other fish in the tank and none appear to have any issues.
Any ideas what this spot is? Should I quarantine the fish? Catching him will not be easy.
Any ideas what this spot is? Should I quarantine the fish? Catching him will not be easy.