Uumm they sometimes can be agressive towards other fish - I think they are classed as semi-aggressive or something, so just be careful with what you put em in with - sometimes they try and attack some of my fish but they are big enough to defend themselves. Get a reasonable size group of them and you will definetly see the benefits. Just provide places for them to hide etc because mine can be quite skittish sometimes. Also mine enjoy squeezing themselves into narrow spaces then getting rescued by me so watch out for that.