Cory catfish are peaceful scavengers that spend their time at the bottom of the tanks. Corys are social fish that should be kept in groups of at least 5. Since these fish are peaceful, they will not defend themselves against big aggressive fish so they should be kept with small or medium fish that are peaceful. They will be seen most of the time swimming around the bottom of the tank going through the substrate looking for food scraps. They will help keep the tank clean, however they will not pick the algae off of decorations or walls of the tank.