Skirts don't always nip. It's just a real possibility with how the hatchets hang at the top. I would keep the hatchets and get a different tetra. If it was me, I'd do Cardinal Tetras or Neons, in a larger number. Black Skirts fade out as they get bigger. I'd go for something with color. As for the Hatchets, I'd get Marbled. Their color pattern is way better than the Silver or Martha's.