Twinty commonly used commez-Lca’l, disinfecto.nts (disinfeo- tnts, nntiseptics, sanitizers and detergents) were evaluatedfor their virucidal activity against two viruses the Poliovirus type 1 ar.the Vaccinia-virus~ Many trials were assayed to pro-duce a suitable antigen. We found that the adventitious protein in antigen within the limite of 10 mg ./ml had no influence on .the virucidal activity of both betadine and formaline; As well6 loglOI.D/m1~ virus titer was found to be sufficient if virus”;virucide mixture was completely separated his work is a trail to take a step forward as regardsthe development of a standard technique for the ~aluation ofthe effectiveness of virucidea . After a. contact period between’.virus and virucide the mixture was filtered through a gelcolumn. to separate the virus completely from the virucide aco- rding to their molecular dimensions. The tested disinfectants were diluted as recommended by the manufacturers.The virucidal efficienoy of the virucides was judged bythe time required toinactivate 4 loglO I.D./ml. virus/ml.sources. The fish should be examined before its enter-ance to the fish ponds.Periodically, laboratory examination of water andfish samples should be carried during the productiveseason which is important to minimize the risk of infectivefoccus formation.Two weeks, previously any infectious disease occured,pond must be dried off and disinfected with suitabledisinfectants.Generally, each pond must be constantly observed tomake sure that the favourable conditions concerning fishhealth and production are present. The favourable condi-tions of fish are the cleanliness of pond and harmfulsubstances must not be more than their permissible limitsfor fish production such as hydrogen ion concentration,un-ionized ammonia, dissolved oxygen, carbon dioxide,nitrites, nitrates, hardness as Caco3 and salinity ).Moreover, taking off dead fish from the ponds, as soonas they float and applying their proper hygienic disposal,are essential to avoid water pollution which may subseq-uently result in further fish infection