An adult you can feed a bit less than 10% they slow down growing when they reach adult status. The real question is how heavy is he? They don't just become adults like most things do when they are X years old. It is almost always about weights. Usually a male I would consider an adult in the 1000+ range. Females in the 1600gm + range. Adult being able to breed consistently there are always exceptions just this is my general guid line.