Yeah, danio fry are much different than cichlid fry. From size to parenting to growth rate to foods, it's all different.
As for what to do with the crookeds, there are a few reasons fry develop those crooked spines. Genetics, water quality, vitamin deficiency and disease being the main ones. So the chance of these fry carrying a disease is possible but by nature, fish eat the dead, infirmed old and diseased fish out in the wild so there is the possibility that nothing will happen if you feed them to your barbs or they too can now carry whatever the disease is. Since these fish are new to you, there will not be any definitive answer to the cause as you don't know what they went through before you got them.
For me, I put
everything else out of my mind and just ask this question: " What is the best thing to do for the fish colony?" 99.99999999999% ( because nothing is 100%
) the answer is "get rid of them." If you don't want to chance the cause being disease, don't feed them to other fish. If you are willing to possibly losing your Barbs, feed them to the Barbs. Just be sure to be okay with whatever happens from your decision.
When it comes to breeding, culling is an important part of the process. We have taken away the natural ways these deformed and diseased fish are gotten rid of in nature so you have to play Mother Nature in order to keep the fish stock healthy. Just look at all the balloon fish and deformed fish that are now part of the hobby because the breeder didn't want to cull them. The fish suffer shorter lifespans, internal disfunctions, reproductive issues and more. Talk about not being fair to the fish....
That's just the cold hard facts.
Hope this helps.