Personaly I have had reptiles all my life. What kind of turtle is it? I used to have a couple alligator snapping turtles...if you keep fish with a meat eating turtle it will eat them till its full...if you keeped a large amount of, oh I dont know, guppies in there that would keep reproducing he should only eat when hes hungry. (sorry...very long run on sentence lol.) Deffently wouldn't keep any kind of fish that you are attached to, cause they will eat them. (dont anyone get mad at me over the guppie thing...I'm talking regular guppies not the fancy tailed) As for the salmonella, the best way to keep from getting it is making sure your animal is healthy before purchasing it, and ALWAYS WASH YOUR HANDS after handleing it or any of its items. But as I said I have been around reptiles my entire life and never got it. (my mom had a 4 ft boa when I was 4...and we have had snakes and turtles and lizards ever since
) But I will tell you, turtles are VERY VERY dirty...lol...cleaning up after a water turtle sucks! Trust me! I'll never have one agian just for that reason. Now Tortises on the other hand...but its up to you. Do your research on the type of turtle you get. Thats the best way to go.