hi, i finally got aorund and bought a 20 gallon for one normal corn. he was the one that was always trying to mate and was always causign problems. no hes by himslef. and for the other two the go tthe 55 galon the them selfves. i have never had any problems with the other two the alywas sleep toghter. if i do see any sighnes of stress i will by another cage for one of them.