Dojo/weather loach growth/tumor

[Pywakyt]

Saw my dojo loach for the first time in months today and I noticed he has a growth on his right side right near his fin about the size of his head. It kind of looks like cauliflower in shape. He's about 8 years old. I'm wondering if anyone has any sugestions what it might be or more importantly how to tell if he's in pain and should be put down or if it's ok to let him live with it.