He climbs to the top of the glass, spreads himself out, and floats around upside-down on the surface. A tetra bumped him, and he curled up and sank to the bottom, so he definitely wasn’t stuck up there. The second he hit the substrate he went right back to the glass and did it again.

Why? Whats his deal? We have a handful of assassins and none of the other ones are doing this. He only does it when the light is on.