THERE IS CURRENTLY NOTHING IN THE TANK EXCEPT SAND AND LIL BIT OF LIVE ROCK. WILL BE ADDING MORE LIVE ROCK AND CRABS THIS WEEKEND. THE THING ON THE BACK IS A REF-FUGE. IT BASICALLY IS ANOTHER TANK THAT ACTS AS ANOTHER SOURCE OF FILTRATION AND A BREEDING GROUND TO BREED LIVE FOOD FOR THE FISH. WONT BE ABLE TO PUT ANY FISH IN IT FOR A MONTH. RESASON BEING THE TANK HAS TO CYCLE.