dont use clear divider or put background on it...problem solved!!
but i guess it would be a little trouble if you are still thinking about half/half tank

just a quick idea...since they cant really jump or climb divide the tank with decorations. something like a water fall in middle run down to both side, it should be fine if it's tall enough without too much slop.....(damn it, now i cant get it out of my head...i think i enjoy building the tank too much)