I have bumblebees also I haven't had them but a couple months. Love to watch them...still trying to figure them out. I have two that are larger and two that are smaller...I know one is a male for sure he is almost black..All of mine are pigs. I feed them out of my hand...like pirannas...Recently one of my smaller one has started looking funny..fins are frayed and starting to look white on its side. Other smaller one fins look slightly frayed..figured they were female and the large male was beating them up..so I move them to my QT tank...well now the one that looks the worse for wair is hanging out about a half inch from the top of the water...moving her fins real fast...have treated with melafix and pimafix and leave the light off in case it is stress...Anyone have any suggestions for me on this?