The butterfly fry are 4 weeks old now and I finally found time to do their first intensive cull, which strangely left me feeling simultaneously demoralized and hopeful. In this cull I was looking for any fry with crooked backs, collapsed tail fins, or a single tail fin. Since they're so small yet, those are about the only culling parameters I could use. Even so, I ended up culling out about half of the fry, which is where the "demoralized" part comes in. One odd thing I noticed is the vast majority of fry with crooked backs actually had very nicely spread butterfly tails. It makes me wonder if some or all of the genes controlling the butterfly tail formation in the parent fish are linked to a mutation causing crooked backs. If so, that would be pretty unfortunate. But I'm not sure if that's the case, it was just a thought.
So, I'm feeling a bit disheartened about how this batch of fry will
turn out, but it's probably too early to judge them that harshly yet.
For years I researched about goldfish breeding, so I know that with the
fancy varieties, very few (if any) of the fry actually turn out as nice
as the parents. Still, it's one thing to read about it, and a totally
different thing to experience it for the first time. I still have hope
of course, thanks to a few of the fry that look to be developing very
nicely. Here are some of the best that I plucked out from the main group. Aren't those little tails so pretty?