Clown loaches don't grow as slow as people say. They tend to grow to 4-5 inches in length in under a year. Then they start to grow in body mass as well as length, putting on a half inch to an inch in length per year after that. A proper sized group of clown loaches after a year has pretty much almost outgrown a 55 gallon tank. A 90 gallon tank would last much longer for them than a 55 would.