Have some moss and plants for them to forge on. It also controls the nitrate and ammonia level. Try your best not to use Anubias or Crypt plants, but if you have them just please try your best not to trim the plants (leaves and stems) inside the shrimp tank. Especially never cut the rhizome of the Anubias plant and plant it back right away in your shrimp tank. Freshly cut rhizome/roots/stems/leaves from Anubias and Crypt. Plants (especially Anubias) leak a toxic substance to your tank. If the shrimps forge on it, they tend to die within several days. Or if you observe your shrimps swimming like crazy in your tank after you trim the rhizome of the Anubias plants, then you know you will have to take out the Anubias plant and carry out 80% water change right away. However, if you have great filtration/circulation in your tank, then it "should" not be a problem depending on the size of your aquarium but I will still recommend to carry out a water change just to be on the safe side. Do not use fertilizer if it contains copper for it is toxic to shrimps in general if the shrimps are housed in an aquarium already. If you still want to use fertilizer, then I would recommend just using Seachem Flourish and cutting the doses stated in the bottle by half or more, depending on how much plants you have and the growth rate of the plants themselves. Java moss, peacock moss, string moss, Christmas moss, Fissiden sp. moss, or any other moss would work. If you have driftwoods or stones, tie your moss onto it using threads or very thin fishing line. Over time, your moss will grow very nicely (forming shapes) and your shrimps will have other grazing areas including areas for them to hide as well.
Ammonia has to be absolute zero, and nitrate has to be at a minimum. These shrimps love clean water so 30% to 50% water changes weekly is highly recommended.
CRS/Black Bee shrimps and Tiger shrimp cannot be housed together because they will interbreed and their interbred hybrid offsprings will look nothing like their parents but tend to resemble their "Tiger" parental shrimps. Because of that you will not get anymore pure CRS species which means all of the money you have spent on high grade CRS will go down the drain.