yeah u wont have a holiday if u keep marine fish water conditions must be checked daily. piranhas are dull they r not the savage fish people think to get em eat that frog i sat watching for least 1 hour they r scared so easily i walk in room and they smash in to glass. my best set up was community fish like angels, with cray fish(lobster looking thing) frog, senegal bircher + small snakeheads there was well over 30 fish in that tank looked well smart angel would come up to the glass wen got in from work, i came in once and the senegal bircher had the small frog half way down its throat with just its legs hanging out the mouth kicking, and the cray fish i saw that grab fish right out water and cut em up n munch em. fish keeping is awesome