I have been dealing with micobacterium marinum since February! On antiobiotics all this time...may be able to go off them end of June...maybe! It's a killer! Rare. It all came from a small cut on the tip of my rt index finger. I do have a fish...a beta. This bacteria is a water borne bad boy. I don't know for sure, but I think cleaning the fish bowl was the open door for this bacteria. We caught it in time, prognosis is good. But I have learned a lot from it.
If you have an open wound, it's a good idea to stay out of lakes or ponds and, yes, the ocean, too! The bacteria is there, also. Wear gloves when cleaning anything fishy. So, a word to the wise.