Like Caspian said, need to know species.

General rule of thumb with Newts though is they are too shy to be kept with fish. When kept with fish they usually become stressed. They also require cooler water than most tropical fish can tolerate.

Mixing amphibians is a big fat no. There is a huge risk of cross contamination of disease, toxins, parasites. You name it, it's just a cardinal rule of keeping amphibians in general. You want to go with a species only tank with these guys, for the most part (and amphibians in general).