I agree with Midgetwaiter
Go with the 48" for swimming room
I have 7 clown loaches that school together and the largest is about 5". If he leads the pack then they make sure to go from one end to the other, if a small one leads then they only go about halfway, and as yours are larger I would give them the length to swim.
If you plan on putting them in a larger tank later then maybe add a couple Bala sharks to go with them, mine get along great!!
Or just buy my 5' tank that is for sale!!
