I was given a brown African knife fish about a month ago and he has seemed to be doing fine just hides a lot but that might be normal for I don't know.... Anyway I found him this morning and one of his eyes is bulging out... The only thing that has changed is I have added a large angelfish to the tank but its a very nice one and use to live with tetra so I don't think she is picking on my ABK.... Any ideas???? I think he is 1-3 years old