Penaeus monodon juveniles (PL₅₀) were fed live and decaying aquatic macrophytes and a commercial grow-out pellet (40% crude protein) in 80-l glass tanks over a 30-day period. Growth and survival were significantly higher for juveniles fed some form of macrophyte compared to controls (pellets). Survival was highest with live Najas graminea (100%) compared to decaying Ruppia maritima (65.4%), live R. maritima (58.9%) and pellets (52.5%). Juveniles fed decaying N. graminea had the lowest survival rate (30.6%) but the best growth (7.8 mm carapace length (CL), 37.6 mm total length (TL), and 0.2587 g body weight (BW)). The latter body sizes were significantly greater than for juveniles fed pellets (6.2 mm CL, 0.2338 g BW) and other macrophyte treatments. Prawns fed with live R. maritima showed the poorest growth (4.5 mm CL, 24.7 mm TL and 0.1070 g BW). Aquatic plants are directly grazed by penaeid juveniles, or contribute to the detritus fed on by prawns and other benthic organisms. Aside from food, macrophytes also provide cover or shelter from predation and cannibalism.