Can a cup rip a platy? Or is it fin rot?

[NinjaNomad196]

We went to do a water change, and we don't have a back-up tank, so we put him in a cup for 5 minutes to wait. Yes, it had water btw. Even through the past few days he's been getting repaired (his tail is regrowing ) he has done some stuff. Are these symptoms of fin rot: Getting REALLY excited and happy and active when the lights on, hiding in a corner the WHOLE time the light's off. And in the corner, he rubs his tail, which is fixing up, and you can see slime in the corner from his tail

 

[NinjaNomad196]

Don't worry, I won't cup him again, I'm soon upgrading my tank, and he will be placed in the old tank instead of the cup for future reference.

 

[Oohitsae]

if the cup has sharp edges, then it could most definitely have ripped him.

Fin rot looks like the edges of his fins are melting or like they may have been singed (dark coloration) - best way to treat is lots of warm clean water. Aquarium salt can also help speed up healing, but isn't necessary.

Are you sure it's his slime coat? Is it fuzzy, or clearish looking