Just watch out that the shrimp dont end up in your filter, they are shockers for getting in through the smallest of openings, and trust me its hell once you realise the filter media you have just gone to great pains to clean was actually housing quite a few mischevious shrimp.
If you dont already I would look at adding some leaves to your tank for the shrimp. Indian Almond leaves are often used, but these are usually sold dried and will have some impact on your pH over time. You can also give them green, yellow or dried mulberry leaves and fresh organically grown kale. Shrimp really will go for almost any food and I know of one person who gives them fresh banana, not the skin or leaves the actual fruit.