I need some advice and opinions

[Jade123]

Hi! I need some advice and opinions on the situation I’m having- I have a chonky oranda (I don’t know for sure if it’s an oranda the pet store told me it was) I’ve had him for nearly a year now with not many problems apart from him being a little aggressive towards other fish- I recently decided to add another fish as my older one died of fin rot. My oranda was a little aggressive at the start but shown no interest the next day and everything was fine, today I’ve realised my oranda has started to get red around his fins and started rubbing on the gravel at the bottom of the tank I’ve tried to do some research but I’ve got multiple answers and I’m sort of clueless. I’ve attached some photos for better imagery of what it looks like. My other fish is totally fine , they’re both eating normally so I’m just confused on why this has happened

 

[Aiken Drum]

Not a great quality photo, but it looks a little like a wound?

Can you give some more details on the tank? How big is it? Water parameters? Other fish in there?