Not sure what this is. Or if it's okay, I have just noticed either he's shedding his tail or something or its just whiteish and he sits by heater. Any ideas.
Check your parameters. I've seen fish shed scales because of ph swings, ammonia, nitrates. ECT. Do a big water change and use a antibacterial like pima fix. If he grows white fuzz around the wound area use mela fix. For fungal infection.
The parameters are fine I checked them about 4 days ago and everything was normAl. I only have another eel, 2 Cory cats and 2 plecs. I will get some tomorrow I have tank up at 81 right now for him his tail was like this when I got him in pretty sure