Generally we use brine shrimp lethality bioassy method for in vitro cytotoxic activities screening. For this we have to hatch brine shrinp. which temperature is suitable for hatching brine shrimp?
I don't know much about brine shrimps, but if I were you, I'd "Google" brine shrimp to see where its natural habitat is (temperate or tropical) then match your hatching temperature accordingly. You might also ask the supplier of the shrimp spawn, or look in a reliable published paper which uses this assay.