Heya Charles.
We chatted briefly about the diet some time back.

Like Mr Francis I had a marcianus female have a litter at just under a year old being fed a diet consisting of a good portion of the fish jell-o. I've only made it with trout & salmon though, never tilapia.
Only one baby died (it wasn't an eater out of the chute) but all the rest are still healthy and thriving with no noticeable issues. Pretty normal litter imo.

I have cut back a bit on the jell-o in recent months though and have been feeding a larger portion of worms than before along with the jell-o. I've also always added mutivitamin to my fish mix as just meat, bones & B1 I didn't feel was complete enough & lacking the nutrients from the "guts" they get in whole animals. It's also why I stepped up the worm portion a little higher.

I'm not sure I'd be so quick to attribute the issues to the diet though. The spinner kind of problems you're describing aren't usually diet related, at least in other species. It tends to be a defective genetic thing.

Something to keep en eye on for sure though.

This thread is making me hungry