big eyed fish (black more)

Question
Yesterday my daughter noticed on one of the fish he was missing and eye. He seems fine is that usual?

Answer
No, that's not usual, and no, it's not fine. Most likely you haven't been doing regular enough water changes, and something built up in your aquarium, some form of disease or parasite. The best thing you can do now is just always do a 15-25% water change every week or every two weeks. It's the only thing I can think of that would help. Make sure you don't overfeed either. Remember, a fish's stomach is about the size of their eyeball. They don't need to eat much.