Is my fish in pain? :(

Hello, I’ve had tropical freshwater for over a year now with minimal issues. However I’ve noticed something growing on my guppie for the past few weeks. I wondered if it was an injury at first and kept an eye on it but it’s getting bigger and bigger. I’m worried it might be cancer because I know these types of fish can be inbred in captivity. He’s eating fine and very active and seems his normal self but if he isn’t going to get better and is likely in pain then I would prefer to do the right thing. Please look at the pictures and advise? All the other fish in the tank seem fine and aren’t bothering my gorgeous yellow

Has the guppy always had a black patch, or did that appear at the same time as the lumps?

Appeared the same time as the lumps.

The scales sticking out from the body would suggest a bacterial infection.
The black patch is dead or dying tissue.
The lumpy bits could be cysts or tumours.

I would euthanise the fish because it will be cheaper than trying to treat it and the odds of successfully treating it are quite low.

I’m afraid I have to agree with Colin_T. It’s painful just to look at it. I’ sorry.