If he does have a disease or bacteria, can I get it by touching the water?
I'm still new to fish - but from what I've read, the only problematic 'fish disease' that people can 'catch' is something called Mycobacteria.
It's a fatal disease in fish. But in people, it can enter the skin through cuts or wounds and can cause a nasty infection.
If you have any cuts or scratches on your hands, you can wear latex, nitrile or rubber gloves to protect yourself. And, as Kithy said, always wash your hands after you finish water changes, or moving tank items.