Have a look in the gallery, you will see one of those catfish in there. I have two of them, both around 5 1/2 to 6 inches long. You will have to post a picture of him, but if it is similar to the ones I have got, that is about as big as they get. They are really nice addition to the tank, they are not very messy fish which has the great advantage when keeping Oscars. The only drawback with these type of fish is they are nocturnal and they don't really do much during the day. If you turn the lights off and observed from a distance, you will see them come out straight away and start swimming around the tank looking for food, this is the time to feed these fish. If you try feeding them during the day, the chances are they won't feed, especially if you have given them somewhere to hide which is a very good idea. One of mine lives in the great big pot, the other one lives under some wood. Some people say that you should keep these in groups, I disagree, I have two and they don't like each other at all, they never spent any time together, they keep themselves to themselves.