with 4–5-day-old PL at a density of 4050 PL m3. All raceways were equipped with high
pressure rapid sand filter, a pump, a center longitudinal partition over a 5.1 cm PVC pipe with nozzles, eighteen 5.1 cm airlift
pumps, six 1 mlong air diffusers and a 5.1 cm Venturi injector. Two out of the four raceways were each equipped with a home-made
foam fractionator (FF). Average water usage in the two raceways operated with FF was 3.35% d1 compared to the 9.37% d1 used
in the other two. Shrimp in the raceways operated with FF and the lower water exchange had greater mean final weight (1.91 and
2.0 g vs. 1.73 and 1.43 g), survival (100 and 92.4% vs. 55.9 and 81.8%), yield (7.64 and 6.89 kg m3 vs. 3.92 and 4.74 kg m3) and
FCR (0.97 and 1.06 vs. 1.36 and 1.64) values than those operated without FF and with higher water exchange rate. Disease
diagnostic results showed no signs of viral pathogen infection.