I agree it was probably moving them no matter how carefully you did it. Tiny fry are just fragile. In fish that have huge spawns there are also huge losses. I think you've done a great job.
I'm not sure if your corys are the same species that wasn't clear to me. But, please, not more hybrids...Just because you can doesn't mean you should. Sorry, now is not really the time or place for my rant...You did start it...
No no i dont WANT to breed hybrid cories! Lol
I have weitzmani corydoras with my other cories in my big tank.
History:
I found an oddball cory at the store, mixed in the trilineatus. Turned out it was a weitzmani. I found 2 more at another store so i had a trio. Given theyre social, i wanted to find more of them. In canada, i only really have limited online options and weitzmani arent one i can special order at my lfs.
I managed to find some online finally in stock, i bought 2 more but paid $50. One i thought was male was sickly from the start, his barbels were in bad shape and he was thin when i got him. I tried getting him back into good health but he just kept going downhill and his whole mouth rotted off. He eventually started having seizures so i had to euthanize him.
I thought he was my only male.
Fast forward to now, one of my remaining 4 has been doing the boy cory dance to every gravid female he can, though theyre not interested lol. Just gets in their faces and does this little wiggle dances lol im happy to see that one of my remaining weitzmani is a male. Once my other weitzmani are mature, i will separate them to another tank to breed only them together, not with other species.
But because my other weitzmani arent mature yet, the boy is going after my aeneus cories and the new sterbai who share a tank with him.
Im just happy to see there actually is a boy there. Id like to increase my weitzmani shoal as theyre a timid cory species, but theyre expensive and hard to find.
This is the boy who is getting carried away with his new-found hormones...
And the other 3 currently with me
^ this one is my youngest but i suspect she is a female. Fingers crossed. She was one of the ones i ordered online.
And this was the poor dude who didnt make it.