shrimps eating plant

Hi All, Currently i have the following shrimps in my shrimp only tank with dimension (16" (W) x 9" (D) x 10" (H) ) Caridina babaulti (Rainbow Shrimp) - 15 Nos. Caridina gracilirostris (Red Nose Pinnochio Shrimp) 5 Nos. Caridina sp 'Zebra' (Zebra Shrimps) - 7 Nos. Caridina hodgarti...