I've noticed that my new batch of smaller (3-4") RES in my aquarium don't seem to be quite as light sensitive to the aquarium lights as the the larger ones I had in there. It took three or four days before they started favoring the the darker end of the tank. When I put the larger ones in back in October they immediately favored which ever area of the aquarium was the darkest. Function of age, size, or development?
