Yes they are big for a 55 but with clean water good filtration and good quality food they would be fine.....it is temporary he said he will have his 300 up and running within a month. They are better in a 55 than they were in a 30! I am just running out of options here. They have been moved back and forth between the 30 and 500 I wish I had something inbetween those sizes but I don't. I wasn't expecting my BF to bring me home $250 discus! and then for my mama sting ray to give birth that same night! Trust me it is a mad house here. The loaches got moved back to the 500 as they wouldn't leave the discus alone at least in the 500 mama sting ray can get away from them. She has a little sore on her bottom flipper where my male bit her mating and that is what the loaches are pestering they just keep picking at it. I am a very good fish keeper and to imply anything else is just not fair. I would like nothing more than to keep them....they are one of my favorite fish. I just want to get them into a new home.