Be careful when cleaning your fish tank!
Perhaps it comes from the danger of anthropomorphising our animals that some people don't seem to think they can pose a danger to us through their very nature - different species harbour different micro-organisms, and what might be good and natural for one is quite bad news for another. Bird fanciers can get ill if they do not take common sense precautions (such as 'pigeon fanciers lung'), those looking after rodents might become infected with rat-bite fever, or even a form of meningitis, whilst reptiles can, like other species, pass on Salmonella. But what about the fish?
Fish obviously don't operate in the same environment as us gas-guzzlers, (or if they do, then it doesn't tend to be for very long). But what this means is that we are less likely to become infected with any bacteria that has evolved alongside them: we do not pet or stroke them, we do not (hopefully) kiss them or let them them share our beds. Yet despite this, contact can be made when it is time to clean the aquarium.
The main culprit that fish-owners should look out for is Mycobacterium Marinum, a bacteria that lives in the water. It causes opportunistic infections in humans by getting in to the blood via cuts and existing lesions. The fish themselves can also infect their owners by a bite or by simple contact. The bacterial infection causes lesions that may take some time to develop, but there are other ways the bacteria might infect you.
The story of a retired bus driver who used to syphon off the water in his fish tank by sucking on the end of a pipe is a chilling reminder of how inappropriate cleaning methods can put your life in potential danger. Unknowingly, the bacteria got into his lungs, and it was only after months of medical investigation (including a cancer scare) did they discover what and how it had been caused. Fortunately, the gentleman was saved by an antibiotic cocktail that killed off the bacteria and he has publicised his story to warn others of the perils of fish tank cleaning.
So whenever you are looking to clean out the homes of your pets, whatever species they are, they will likely have some potential micro-organism that can, if you do not take simple precautions, cause you harm.