They will eat just about anything, I have read that if their diet has too much protein it can cause them to grow too fast which can cause them trouble when they have to moult. I give them goldfish flake as it has more veg. They do like vegetables anyway spinach seems a real favourite just dropped in boiling water and then fed, peas, beans, lettuce, cabbage, dandelion and nettles are also good (blanched). Leaves like dried oak, beach or Indian almond leaves are also good for shrimp, I think part of it is the stuff that grows on the leaves in the water as they decay but they also eat the leaves. I also feed them oats, sunflower and other seeds.