We lost four newtlets today. I don't know what caused it, but the container they were in didn't seem to be completely clean. It had some sort of slime or mucous that didn't wash out with hot water alone. If that's what caused it, it may have clogged up their gills or something.
I may need to clean the containers with a brush instead of just rinsing them.

Oh well. Some losses were to be expected from a first-time newt breeder. We'll see how they are tomorrow; at least they're eating heartily.