Weird pustule on watchman goby’s face?

[Richard K]

I’ve found a weird pustule on my watchman goby’s face, no idea what’s caused it but he doesn’t really seem to care.

 

[Jay Hemdal Verified Community Expert]

I’ve found a weird pustule on my watchman goby’s face, no idea what’s caused it but he doesn’t really seem to care.

I see this once in awhile on fish posted here (clownfish mostly). In 50+ years, I've never had a case in my own fish, so I can only go on reports from other people.

These are clear fluid filled vesicles of unknown (to me anyway) origin. They are sometimes fatal. I have guessed that their cause is viral, but there is no way to know for sure.