i keep alot of fish with my cats, have never seen them eat anything alive. i keep them well fed they dont mess with my stock list. when they get larger a little 6 inch fish swimming by may trigger something where as a 22" fish wouldnt. they wont be that hungry. i have a 2" jack dempsey, a 3" jag, a 4" gt, all growing in the pond with multiple cats well over 12" and growing fast. i also have a pair of red devils that have been protecting there fry from the rest of the fish (including 4 more red devils) for a couple weeks. with enough room and food even large cats tolerate smaller tank mates.