I had 7 angelfish in my 55 gallon tank that I got off Ebay. All but 1 of them came to me pretty small, about quarter size, and the 1 other was over 1/2 dollar size. All had been going good then they started dying..2-3 a week until now the only one I have left is the large one...which has gotten VERY big. I don't know if i is male or female, but there is a "breeding tube" visible. The water parameters tested great with the API master kit..2x weekly water changes..all eating well..they seemed fine til mornings, then there would be another one dead etc. My daughter said she saw the big one chasing the others a lot. Is it possible that it chased them to death? Could this be some kind of "I want to breed with someone" thing???