really cant help without water test results get the test kits!!!!! very important when owning a saltwater tank. my fishes almost died one time they all looked out of breath and like laying around i found my water was not oxygenated meaning i did not have enough oxygen in my water, also u can use your powerheads to oxygenate a tank point them up to cause small waves like the ocean those waves put oxygen back into the ocean, yes fishes breath oxygen but in a different form. so i bought a tiny pump and stuck a lil stone to give me bubbles in the back chambers an never again have they done that, also if a room is very humid and hot that can cause the water to hold less oxygen and the warmer your water is the less oxygen it holds. so please test and come back and tell us your results.