Populations of marine red yeast from shrimps and the environments of shrimp culture were investigated from various areas at Zhanjiang in China. All strains were studied for the production of biomass and carotenoids. We isolated 88 marine red yeast strains and the average populations of marine red yeast in seawater and the water from shrimp culture ponds were 70.0 and 172.4 CFU per 100 ml water, respectively. For shrimp samples, average populations of marine red yeast from gills, intestines, and stomachs were 178.0, 15.0, and 8.0 CFU per shrimp, respectively. The isolates were grouped into nine species belonging to three genera as follows: Rhodosporidium, Rhodotorula, and Sporidiobolus. R. sphaerocarpum had the highest average biomass yield (10.3 +/- A 0.88 g/l), followed by S. ruineniae (10.1 g/l) and Rh. mucilaginosa (9.9 +/- A 1.75 g/l). R. paludigenum had the highest average carotenoid yield (2.83 +/- A 0.589 mg/l), followed by S. pararoseus (2.72 mg/l) and R. sphaerocarpum (2.59 +/- A 0.454 mg/l). The results showed that marine red yeasts were normal microbial components in the environments of shrimp culture and shrimps, and carotenoids are abundant in these marine red yeast.