I'm worried about my 10" male trimac. He used to be more outgoing, but now he resides inder a pre-filter intake sponge most of the time. He comes out to eat occaisionally, and will attack me through the glass if he is in the mood, but mostly he sits very still under the sponge. He is not gasping at all and doesn't look distressed, but I am worried about him. He is only 2 years old and he is alone in a 5-ft, 100 gallon tank.