Fin rot, or just not friends?

[DiscGolfRob]

firefish and Midas blenny in a 20 gallon quarantine, together. Have not treated, just observation. They have been together for a week and a half. I have seen minor aggression, but very rarely. I know this is a possibility for these two fish. I am more concerned about the discoloration. Does this look like nipping, or could it be fin rot? Thank you for any help!

 

[EmdeReef]

It could be an injury. I would continue observing and then treat based on color around and if it’s visibly getting worse after a couple days. If it does get worse then it’s likely a bacterial infection.

Also keep an eye out for aggression.

 

[Humblefish]

Midas Blennies are notorious fin nippers IME.

 

[DiscGolfRob]

It could be an injury. I would continue observing and then treat based on color around and if it’s visibly getting worse after a couple days. If it does get worse then it’s likely a bacterial infection.

Also keep an eye out for aggression.

Will do. Thank you so much for taking the time to respond!

 

[DiscGolfRob]

Midas Blennies are notorious fin nippers IME.

He's sneaky about it, but I think you're right. Thank you for taking the time to respond!