in my experience, they can be rowdy but right now i have mine in 30 gal planted with some serpae tetras, and some ottos. they love to eat small fish if they can catch them that is. but if u have enough cover the fish can hide. i would not advise a tank less than 55 gal, which mine will eventually go to once i get it going, just a bigger territory for them to hang out in. also caves are very good for them.