That's just parts out of a T-8 or T-12 fluorescent light fixture, the plastic piece running between the two "tombstones" is a probably a wiremold cover. I would junk all that and go to Home depot and buy a new 4' 2 lamp shop light, they are pretty cheap. You may even think about buying the water proof model, it'll cost a bit more though. If your tank has glass tops then the waterproof model is not necessary.