All of the above post are spot on. I have a 10 gallon cull tank in which I added
wcmm's as my first experiment with a shrimp/fish tank. The tank is heavily planted and I am now starting to see babies, both tiny and a bit larger. The tank is heavily planted so the baby shrimp have plenty of places to hide.
If your tank is not planted or the plants haven't grown enough, may I suggest putting in
plastic plants for the time being so the babies have a place to hide? You can even make very cheaply, a breeding mop, look on you tube for instructions. While some fish are said to be shrimp safe, endlers being at the top of the list, any fish is going to find tiny baby shrimp a tempting treat. I have resigned myself to that fact in order to have the beauty of a fish/shrimp tank and I'm sure I lose some to the fish, but keeping enough hiding places makes sure the shrimp colony has enough survivors to keep it going.
And they will hide, they are masters at it. You may think you don't have any and then one day you notice a population explosion.
The only other thing I would like to mention is if you have a hang on back filter, you might want to cover the intake with a prefilter or even just a fine mess bag or panty hose. Not only does it make sure you don't suck up the baby shrimp but also any endler fry you might get. It's kind of a pain since you have to rinse it off often, I have prefilters on the
hob filters in my community because of the live bearers, which is why I only use
sponge filters in my shrimp tanks.