Have you checked your water parameters? Please post them.
What size tank? Size of Eel?
What is your water change schedule?
How much, how often?
Any other info about the Eel, how long have you had him?
Any other info you can think of might be helpful?
If you can add this type information, others may be able to help you better.
FW & SW
Favorite tank right now - 12G Edge nano fish
As Autumn sauid we need that important info. In the meantime the most important thing you can do is some frequent PWC`s. I`m talking like 15 to 20% twice a day for a few days. Usually cloudy eyes in fish are a sign of not so good water quality.
You can view many of my fish and corals in my photo albums in my profile.