my crs where all adult size when I bought them. some of the females were already berried. but if they are like cherrys at about an inch long. its difficult to tell when crs females are saddled with eggs because of their colour. but you will notice when they are carrying them. you will see the brown coloured eggs under the females swimmerettes. also don't be alarmed if you find some of your shrimp going nuts one night. when the female is ready to mate she will release a chemical into the water to let the males know. it sends them crazy. can be a little unnerving if you've never seen it before and don't know whats happening.