Comparative performance of growing local male Omani goats and sheep were studied using high-fiber pelleted diets supplemented with fish sardine; urea and conventional plant proteins (alfalfa). The fish diet (F-diet) was based (As-fed) on 39.5% date by-products (DBPS) and supplemented with 10% fish sardine; the urea diet (U-diet) was based on 32% DBPS and supplemented with 1.7% urea and the alfalfa diet (A-diet) was based on 42% ground alfalfa hay. The three diets were formulated to be isonitrogenous furnishing 12-13% CP (DM-basis). The diets along with Rhodes grass (Chloris guyana) hay were fed ad libitum to twelve goats and twelve sheep for 80 days. Feed intake was significantly different (P0.01) among diets, with F-diet having the highest value, followed by V- diet and A-diet. Liveweight gain and feed conversion efficiency were not affected (P>0.05) by diets but goats and sheep did differ (P0.05) with goats gaining more (122.5 vs 88g) and consuming less feed than sheep (1500.5 vs 1585g) with better FC (12.2 vs 17.8). Supplementation of high fiber diets with fish sardine and urea significantly decreased cost of feeding by 42 and 45 percent, respectively.