Myobacterium marinum
It is a bit of a mouthful, but this one is not coming from our furry friends. This disease can only be caught from our fishy friends, and more specifically, from their tanks. It would have been a bit weird if they were the only ones that didn’t carry diseases.
Mycobacterium marinum can end up growing inside the fish tank, and you can easily get it if you put your hand into an infected tank without wearing any gloves. It is generally not advised to end up putting your bare hand inside the tank since you can disturb the ecosystem, but this is just one more point against it!
You can tell you have come in contact with this bacteria if you end up getting sores or red bumps on your hands and arms after washing the tank or handling fish, and sometimes they manifest with low-grade fevers too.