Can You Get an Infection From Swimming with Fish?
Bacterial infections from swimming with fish Aeromonas, Pseudomonas, and their direct descendant, Stenotrophomonas maltophilia are all potentially (but rarely) infectious to humans who are older, or immune-compromised.
It is interesting to note that if you treat Aeromonas and Pseudomonas with antibiotics, you can create resistant organisms that are so apparently different from their immediate ancestors that they call it Stenotrophomonas.
Fish may also carry a bacteria (sort of) or Mycobacteria called tuberculosis piscium and that can also be transmitted to older / immune-deficient persons, especially through broken / damaged skin.