All posts above are full of intelligence

, are you using your angel fish to cycle the tank? If you are, I would suggest that you trade them in to your LFS soon. They might not except the fish if their un-healthy. But if you do succesfully trade them, you have two options:
1. Cycle your tank with no fish and something else (info on Fish Lore: Nitrogen Cycle)
2. Cycle your tank with hardier fish: I reccomend Danios.
Hope I helped, and hope your angel fish doesn't continue being suicidal

and you take my advice!
Ali
