I would think you ought to be fine. I have two firefish with a black & white clown, and all three school together. But the clown is absolutely tiny. I got him from an LFS that breeds them, and they let me take him before they normally sell them, so he's doubled in size to barely an inch long after having him for 2 months. With a more fearsome clown there might be some friction, but I think they could hold their own.