Does this look strange to you?

[RedDwarf]

Looks to me as if they are trying to get away from the person with the net prodding them. It's most likely the BB tank that's causing what you are seeing. They appear to be trying to swim through the bottom to get away. Paint the bottom of the tank and they should stop doing that unless they are looking for food.

 

[RandomMistakes]

Looks to me as if they are trying to get away from the person with the net prodding them. It's most likely the BB tank that's causing what you are seeing. They appear to be trying to swim through the bottom to get away. Paint the bottom of the tank and they should stop doing that unless they are looking for food.

EXACTLY what I was thinking. The problem is that they don't know how far down the bare bottom tank goes, so they are trying to find a way past the bottom. Painting it should eliminate this behavior.