Clowns prefer to be in bigger group. The *minimum* that is usually suggested is 5.
They are also fast swimmers and will quickly grow to 4" (and eventually to 14" or more), so they will need a lot more swimming room than a 55 can provide.
ok cool thanksI have 8 Clowns, 2 Yo Yo's and a Zebra. The Zebra is with the Clowns nearly all the time. The Yo Yo's don't normally stick with the clowns, but they are not a problem with each other.
Mine usually hang by themselves or pester my Berney's Catfish.
In my experience, I would see no issue with putting them together.