Chemicals Used in Freshwater Aquaculture with Special Emphasis to Fish Health Management of Noakhali, Bangladesh

Present study was conducted in fish hatcheries, nurseries and culture farms to find out different chemicals used in freshwater aquaculture activities in Noakhali District, Bangladesh. Data were collected through questionnaire interview, personal contact, market survey and participatory rural appraisal (PRA) like focus group discussion (FGD) with fish hatchery owners, nursery and culture farmers and retailers of aqua medicine and representatives of pharmaceutical companies. Twenty two different chemicals were used for different purposes as artificial breeding, pond preparation, water quality management and fish poisoning, insect killing, disinfectant and fish disease treatment in this region. Lime and Zeolite were used for pond preparation and water quality management. Rotenone, phostoxin tablet, bleaching powder and endrin were used as fish toxicant of which rotenone was widely used (70% of nursery farmers, 80% of grow out farmers). Although endrin and phostoxin were banned fish toxicant but these were frequently used in this region. In addition, sumithion, Malathion, diesel and dipterex were used as insecticides. 53% of the nursery farmers and 43% of grow-out owners used sumithion. Triple super phosphate and urea were the most widely used fertilizers in this region. Formalin, bleaching and EDTA were used as disinfectants of which formalin was the most widely (43% farmers) used disinfectant. Four types of feed additive were frequently used in culture activities. Fish health management and disease treatment were the key areas where majority of different chemicals were used. Farmers used six types of chemicals in disease treatment namely lime, salt, potash, malachite green, copper sulphate and formalin where 30% farmers used potash. Oxytetracycline was the most widely used (47% farmers) antibiotic besides farmers used chlorotetracycline and amoxicillin for disease treatment. The study shows that lack of knowledge regarding use of chemicals, appropriate dose, application method and indiscriminate use of chemicals is the major problems in Noakhali District.