Whiteleg shrimp Penaeus vannamei

The whiteleg shrimp is an eastern Pacific penaeid, native from Sonora in Mexico to Tumbes in Peru, that was carried into Asia and now dominates world shrimp farming, with 7.66 million tonnes reported for 2024. It is a benthic brackish-water animal reaching about 23 cm total length, but ponds harvest it at around 20 g, above which growth slows. Two traits drove its displacement of the giant tiger prawn. It has an open thelycum, so it mates and spawns readily in captivity and can be domesticated into specific-pathogen-free broodstock lines; and it tolerates 0.5 to 45 ppt salinity, which opened inland low-salinity farming. It grows best at 23 to 30 degrees Celsius, needs only 20 to 35 percent dietary protein, and is stocked at 60 to 150 animals per square metre. Clinically it is an invertebrate: it has no adaptive immunity and no immune memory, so vaccination is ineffective and health management means broodstock status, screened postlarvae, biosecure water and exclusion rather than treatment. It is highly susceptible to white spot syndrome virus and to acute hepatopancreatic necrosis disease, both WOAH-listed and both capable of wiping out a pond within days of the first behavioural signs.