CONTROL OF Zoothamnium sp. ON PENAEID SHRIMP

Abstract

ABSTRACT Mortalities of two commercial shrimp, Penaeus aztecus and P . setiferus used in pond culture experiments conducted by Texas A&M University in Brazoria and Orange counties, Texas, were caused by Zoothamnium sp. Mortality was attributed to anoxia when the infestation of the protozoan became heavy enough around the gills of the shrimp to restrict oxygen exchange and was prevalent when the dissolved oxygen level in the ponds dropped below 3 ppm. Tests for a potential chemical control demonstrated that 25 ppm fonnalin was effective and subsequent pond treatment yielded satisfactory results.