500 to 50

The shrimps shown in the photo are probably the 8th generations since I first acquired my first batch of Fire Red. Their color has returned after massive casualties (down from 500 to 50) for some reason I am still clueless about. The good news is they have stablised and their color has somewhat darkened in my new tank, sign of ideal water paramater? I am now waiting for some of these precious female FR to "berry" again, in the hope to build back an "empire of red army".