So i have a japanese dragon eel and an African dragon eel together for about 6 months and they get along no problems at all. The other day I noticed this on his tail. They did knock over a rock the other day and don't know of it just got caught under it or if there's a disease or anything it could be? Theyve both been eating great and have been acting normal. Any suggestions at all? Anything i should be treating the tank with?


