I threw the social organisation of both the main tank and the Macropodus tank into disarray yesterday. A friend asked for 8 Macropodus (to replace the fish he had lost during the ice storm). Picking out 4 large males was relatively easy, but picking out the four largest females (and being sure they were female) was more difficult. In the end, I decided that the best way to do this was to catch them all - that gave me a chance to look at all of them and get an overall count. This revealed something that I already knew - a couple of them smallest fish were not well.
I had removed one of the males in the main tank over the weekend because Camallanus worms were, once again, hanging out of him. This was obviously not a re-infection - these were worms that had survived the treatment. While I need to do a second round of treatment, I think I will go with levamisole (provided that I can track some down). Still, the idea of breeding drug-resistant worms did not sit well with me. Two of the others had holes in their sides. They had them when we got home from Christmas, and they had not healed. Anyway, the end result was that I euthanised five fish. Tempting as it was, I couldn't flush them or stick them in the freezer. Long ago, Brian said that there were two ways to kill a rat - one was humane to you, the other was humane to the rat. I decided that speed was of essence, and I decapitated them. Quick, yes, but very difficult on me.
Anyway, I added two males and two females to the main tank, and returned three males (and eight females) to the Macropodus tank. So now the males in the main tank are battling for status. The old male is twice their size, despite being their littermate. The older female though is only about the size of them new males, and is much larger than the new females. She is chasing the newcomers, both male and female.
In the Macropodus tank, the males seem invisible, while the females are trying to reestablish their order of dominance. I still have too many of them, but it's a move in the right direction. With more space and (hopefully) improved water quality, these guys might do some growing.