I have a Red Sea Reef Tank, and one of my fish (striped redish purple with a blue dot on the tail) is looking very robust in the underbelly. The color of the fish is great, and the fish is eating very well; however, this belly thing is freaking me out. Do saltwater fish reproduce? If so, what are the signs, and if the fish is pregnant, what are the steps to take to ensure the safety of this fish from crabs, etc... in the tank? Please help me,...I'm a ROOKIE!