Frozen food and feeders don't really have that much nutritional value. This is a lesson I've learned from master Neil

. Frozen food: cells will start breaking up as soon as they thaw and you pretty much throw nutrients into the water ...not "into the fish". A pretty raw explanation, but you get the point. Feeders, especially goldfish, is a risk too big to take and not as great rewards as on might think.
Best way to go around all the urban legends is: keep the water pristine (I do 80% water changes weekly on African setups, double sometimes of grow out tanks), large enough space and good food. I prefer pellets ..can you say NLS
That's what I thought too. The anal and dorsal fins are too pointy for a female.
Have you documented their growth, size, pattern?!? It's definitely material for a good article my friend.
By the way, do you ship

... I might be interested in either the adults or some of the offspring
My personal choice is way simpler: ONE brand, usually NLS, supplemented with shrimp. Water quality, space and tankmates sometimes do more than just the food they are being served.