Ammonia excretion of green tiger prawn Penaeus semisulcatus as a possible limit on the biomass density in shrimp ponds

The ammonia excretion rate of P. semisulcatus was 0.155, 0.104, 0.048 and 0.036 mmoles ammonia-N per gram shrimp per day for animals of average size 0.6, 1.3, 10.4 and 43.8 g, respectively. A model calculation has shown that for a shrimp biomass density of 400 shrimp/m² and a water exchange rate of 10% per day, the amount of ammonia which would accumulate in a growout pond would be significantly less than the measured 96-h LC50 for these size classes of P. semisulcatus and thus unlikely to cause mass mortalities. Other factors, such as behavioral interactions, would limit the number of shrimp which can be grown in a given pond facility before ammonia would build up to acutely toxic levels. -from Authors