Gymnolinium sp .red tide occurred in May 17 to June 6 , 1998 in Fujian coastal waters .This red tide caused heavy losses to abalone aquaculture .Preliminary concluding :Basic reason of causing abalone death was that Gymnolinium sp .et al had produced some toxins .We studied removal means of red tide organisms in abalone aquaculture on land , the most important countermeasures were listed below:① 5 ～ 20mL/m3 concentrations of Formaldin could kill Gymnolinium sp ., but could not disintegrate them;②0 .1 ～ 0 .5 g/m3 concentrations KMnO4 could control the disaster caused by Gymnolinium sp ..