White patch on Yellow Watchmen Goby

[Brenner Baxter]

Ive had my yelliw watchmen for about a month and a half or so and just today i noticed a white patch near his dorsal fin. Hes been eating well and no other fish have it.
Could he have possibly been stung by my hammer or my flower nems?
Im thinking bacterial or fungal.
What should i use to treat it?

 

[vetteguy53081]

Likely bacterial
Water quality plays a role here and you want to test and monitor: ammonia-ph-nitrate and salinity
Treatment if it worsens will be Maracyn 2 or ruby rally pro