I have used a red filter on my normal cheap lights I have laying around, and there is no change in the fish. Generally all a red filter does is enables us to not have our limited night vision affected. However the fish did come out some, but they still could see me, and the lighting threw colors off. The blue light I notice that they are more active, and if the room is dark, they do not see me very well, the red light this was not true.