Will an 8 inch rhapiel cat take down guppies at night , i have him in my Payara tank to clean up a bit, since i am feeding the live feeders that live in there! Also can he be aggressive at night, i have observed and the payaras just move out of his way when he comes along! He haas been doing an excellent job and would like to keep him, but if he eats the feeders and makes my fish nervous, i might have to move him into a different tank!