My fire eel (about 12-13'') seems to have relocated his home into one of my Whisper HOB filters. He only comes out to eat. I know that this has happened to other people, but is it bad? The water in there must be terrible, should I test it? I don't want him getting torn up or severly stunted or anything
If I cover it any more, the water won't be able to flow out of the filter back into the tank. What should I do? 

