The females will have a yellow "saddle" on their back which the Males do not have. I have males that are very bright red also and get a reasonable mix of males/females in the ones I bought from the LFS. I find the younger shrimp dont have as much colour as the adults and some males are very pale.
I dont think on a commercial scale it would be viable for farms to split the males from the females so you will most likely get a good mix at a LFS as well.
excellent thanks guys in that case i have a good mix of females and males i ordered mine off a breeder on ebay,
what age do they become sexually active? if thats worded correctly lol, and can a female carry eggs without a male present? thanks
Agree with Barney on how to tell them apart. Yellow "saddle" is what I look for in females. Young males are a bit more difficult to tell. Generally males are less colourful and slimmer. Sometimes you get the odd females with less colour and males with more red so not easy just by colour.
It's strange that I find females were in greater proportions whenever I bought any shrimps both from shops and online. At one time I had all females (from different sources) and had to go to LFS to specially pick a male. Unfortunately I still ended up with a female
They should be able to reproduce at around 2½ - 3 months. Females can still carry eggs in the absence of a male but the unfertilised eggs get aborted (kicked off) within a couple of days.