can 6 rainbow sharks go with a red devil and parrot fish in a 55 gallon tank? I have a 29 with 4 very unhappy rainbow sharks in it. I want to get two more rainbow sharks to lower aggression. My sister is setting up a 55 gal in 4-5 months so when they start getting bigger I could put them in there, but she has parrot fish and is planning on getting a red devil. Is this a good idea.