I have been super careful with all of my equipment, and the only thing that ever REALLY goes between tanks is my hands, which are obviously washed thoroughly before and after anything fish related I do. I clean everything really well after each use, so I really don't think that's what it is, although accidents happen. I'm sure it is very worth it, being able to see the difference you make in their lives, and they definitely don't get the love they deserve most of the time. It's just so hard to see them get sick, and struggle, and sometimes die. And yea, the diagnosis is always hard since you can't pick them up and look at every angle, or feel them like you could a dog, cat, or any other non-aquatic critter. A bit off topic, but does anyone have experience with African Dwarf Frogs? I thought those might be a nice break from fish, but would still keep me in the aquatic animal arena (but I'm not saying I'm totally giving up fish, just maybe taking a break).
Kindness and respect should be shown to all animals, no matter if they are furry, scaly, big, or small. Be a hero to the animals and GO VEGAN!