The cherry shrimp will be fine with almost any water parameter. When I got mine I got tired of waiting for them to have babies. I went out of town for 3 days without lights no water top off and came back with hundreds of babies. Oh yeah, they're party shrimps in the dark. As far as tetra with them, the word is no shrimp is safe with any fish, just like me, I'll add fish with mine. I don't think the shrimps will stop producing, just not as many.