Since the devastating effects of white spot disease, shrimp farmers have been trying out various methods to beat the White Spot Virus (W SV). The use of bacterial cultures, feed supplements and immuno- enhancers have, therefore, become popular as a preventive method. A survey was carried out to investigate the effectiveness of these additives.
The survey revealed that 58% farmers used bacterial cultures in grow out ponds. Twenty one percent had no idea of its actual effect. Twenty seven percent used bacterial cultures according to the instructions given on the pack. Fourteen percent carried out regular water exchange even after using them, but, 6 % were able to maintain water quality in ponds without any water exchange for 14 weeks by using them. However 6 2% were affected by the W SV even after using bacterial cultures to treat water. There was no significant difference (X^ test) in the occurrence of black gills, soft shell, and blisters and lesions on the body. However, occurrence of fouling organisms and tail and antennule rot were significantly low in those using water treatment with bacterial cultures.
Use of immuno-enhancers included use of vitamins, squid oil etc. and were used by 55% farmers and 6 8 % has been affected by W SV while using these. Other feed supplements used included egg 38%, raw fish 4%, fish meal 3%, mussel meat 3%, and chicken 2 % . However, 91% of these farmers using raw feed supplements have been affected by W SV.
This survey revealed that most farmers did not have proper technical advice on using bacterial cultures or feed supplements.