Cardinal fish has a growth below the fin

[CKiernan]

This guy has survived a tank crash and is a healthy eater. I never pay much attention to him because he is such a healthy guy or girl. I noticed tonight that he has a prominent growth under his pectoral fin. Is there anyone who can help me identify what this is please??

 

[Jay Hemdal Verified Community Expert]

This guy has survived a tank crash and is a healthy eater. I never pay much attention to him because he is such a healthy guy or girl. I noticed tonight that he has a prominent growth under his pectoral fin. Is there anyone who can help me identify what this is please??

Welcome to to Reef2Reef

Can you tell if this is fluid filled?

How long do you think the fish has had this?

It could be a tumor, but those take a relatively long time to grow.

It could also be a bacterial abscess.