I have a loach (he's yellow, not sure what kind) During the day he chills and at night he's usually very active like other loaches. But tonight I came home and he's laying on his side in the corner of the tank.(I know he's alive cause his mouth and gills are moving) When I fed my fish I purposely hit him with his pellets to see if he would move and he didn't! I know that he hates the fish net so I pretended to try and catch him to provoke him to move but he let me catch him!
I don't know what's wrong with him! None of my other fish are sick, I take fantastic care of them, he's about 4 months old and i don't want him to die!

Does anyone know what's wrong with him or something I can do to help him?