An experiment was conducted for intensive culture of shrimp (Penaeus monodon) in
concrete tanks for a period of 90 days without water exchange (closed system) to determine the
effects of stocking density (25 and 50 juveniles per m2) and bottom substrate (soil and
concrete) on water quality, shrimp growth performance, and nutrient distribution and budget.
Total ammonia and nitrite/nitrogen concentrations in all the treatments remained low in the
safe range for shrimp during the study period. Shrimp weight gain and production was higher
in the treatment with higher stocking density. Shrimp survival and FCR were not significantly
different among the treatments. Nutrient budget revealed that shrimp could assimilate only
23/31% nitrogen and 10/13% phosphorus of the total inputs. The major source of nutrient
input was feed, shrimp feed accounted for 76/92% nitrogen and 70/91% phosphorus of the
total inputs. The major sinks of nutrients were in the sediment, which accounted for 14/53%
nitrogen and 39/67% phosphorus of the total inputs. The drained water at harvest contained
14/28% nitrogen and 12/29% phosphorus of the total inputs. The study has demonstrated
that closed shrimp culture system can maintain acceptable water quality for shrimp growth
and reduce nutrient loss through pond effluents.
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