What do you think is the best shoaling fish? I've got cardinals and rummynose in my tank. The rummynose shoal brilliantly once the room is dark and only the tank lights are on around 10 o'clock. left and right across the glass all night. The cardinals spend most of the time hiding, although a few join the rummynose. Thinking of trading them in for a load of pencil fish or maybe, if money permits.... galaxy rasboras! Although I'm not too sure about galaxy rasboras shoaling much.