Panda Cory’s fins look eaten up

[Averagewater]

Not hate please beginner here got my son some fish last year we have done everything correctly so far with adding stuff and checking water parameters and all that (don’t really know the correct terms) We have a 10 gal tank and had these two panda Cory’s for about 3-4 months and just noticed yesterday he was hiding from the other guys ( the other panda Cory 2 panda mollys & mystery snail) when he eventually came out of hiding his fins looked eaten up . Also the two mollys look like they fight each other I thought one was a female but looks like two males now someone with any advice ? Posted a couple pictures of the lil guy

 

[mbsqw1d]

Not hate please beginner here got my son some fish last year we have done everything correctly so far with adding stuff and checking water parameters and all that (don’t really know the correct terms) We have a 10 gal tank and had these two panda Cory’s for about 3-4 months and just noticed yesterday he was hiding from the other guys ( the other panda Cory 2 panda mollys & mystery snail) when he eventually came out of hiding his fins looked eaten up . Also the two mollys look like they fight each other I thought one was a female but looks like two males now someone with any advice ? Posted a couple pictures of the lil guy

Yeh a good chance at least one of the mollies has become aggressive and taking it out on the cory.
10 gal is a bit small for these fish to be honest. You don't have too many fish for the amount of water, its more that these fish in particular need a bigger space and also need to be in groups of bigger numbers: Corydoras at least 6 and mollies at least 4.

Another issue you have which is a bit more technical and your local fish shop probably won't advise on. Is that these fish need different water hardness. Mollies need hard water, and corys soft. Not much you can do now but its information for future reference.
Without rehoming some of the fish, theres nothing thats going to stop the molly from continuing to attack the cory unfortunately. And once that one has died (probably end up diseased due to stress), then the molly will likely start picking on another one.
I don't know loads about mollies, they're usually peaceful but they can turn nasty if they start feeling claustrophobic.

 

[Byron]

I think there may be more happening here, the cory looks like it may have ich, or some fungus/bacterial issue on its head...will bow to the more knowledgeable members on disease, but this should be looked into.

Agree about numbers, but before you buy any fish you need to resolve this issue whatever it may be, and then consider your water parameters (hardness (GH) and pH). Mollies must have hardish water. Can you find the GH for your municipal water? And the pH.

Mollies need more tank space, they grow quite large. You do not want a female or you will have endless batches of fry uncontrollably. Males only is best, but again the tank size here prevents this. Once we have the GH and pH, we can consider suitable small fish. Many of these will be more sensitive to parameters.