World Aquaculture September 2018

66 SEP TEMBER 2018 • WORLD AQUACULTURE • WWW.WA S.ORG A sia is the home of world aquaculture as it accounts for about 89 percent of world aquaculture production of fish for human consumption in the past two decades (FAO 2016). The major contributing factors in achieving this production are quality seed and feed availability, intensive husbandry practices, disease prophylaxis and cheap labor in Asian countries. But at the same time, development of post-harvest facilities for handling and processing this huge production has been outpaced by growth of aquaculture. From the production points, most of the fish is consumed within the countries where it is produced or exported to other countries. Fish is a highly perishable food item and its quality deteriorates quickly. Hence, maintenance of the freshness and prime quality of fish remains one of the challenging tasks for fish producers, retailers, transporters, traders and processors worldwide. Large production levels coupled with a deficit of post-harvest management infrastructure has led to the addition of chemicals like formalin and sodium benzoate to fresh fish to enhance its shelf- Incidence of Formalin in Fishes in Asian Countries: Some Solutions Sunil Kumar Sahu, Naresh Kumar Mehta, Swapnarani Samantaray and R. K. Majumdar life considerably compared to existing short-term preservation methods such as icing and refrigeration. Fresh and prime-quality fish fetches high prices. Formaldehyde, easily available and cheap, has antimicrobial properties and can extend the shelf life of fish and keep fish appearing fresh for longer time. Formalin is an aqueous solution of 37 percent formaldehyde. Formaldehyde is a very reactive chemical. The gaseous form is known as formaldehyde and liquid form as formalin. Formaldehyde is a colorless gas with a strong odor that is poisonous and flammable (WHO 2002). A very small amount of formaldehyde exists naturally in fish, where it may form during ageing and deterioration. Many marine fish contain a considerable amount of trimethylamine N-oxide (TMAO) that degrades further into dimethylacetamide (DMA) and formaldehyde. Freshwater fish contain much less TMAO, so chances of formation of formaldehyde in freshwater fish is considerably less compared to marine fish. Beside natural Fish is a highly perishable food item and its quality deteriorates quickly. Hence, maintenance of the freshness and prime quality of fish remains one of the challenging tasks for fish producers, retailers, transporters, traders and processors worldwide. Formalin and sodium benzoate may be added to fresh fish to enhance its shelf-life considerably compared to existing short-term preservation methods such as icing and refrigeration. Formaldehyde, easily available and cheap, has antimicrobial properties and can extend the shelf life of fish and keep fish appearing fresh for longer time. TABLE 1. Some incidences of formalin occurring in fish in Asian countries. Lead author Year Species Formaldehyde content Country Hossain 2008 Rohu 13.04 nmol/mg Bangladesh Yeasmin 2010 Rohu, catla Qualitative about 0.5-1% of imported fish Bangladesh Uddin 2011 Rohu Qualitative: about 70% of imported rohu Bangladesh Rahman 2012 Rohu, catla, shrimp Qualitative: about 16.8% of imported fish Bangladesh Goon 2014 Rohu Qualitative: 42-70% of imported rohu Bangladesh Hoque 2016 Rohu Qualitative: about 25% of rohu Bangladesh Bhowmik 2017 Rohu 5.1–12.26 mg/kg Bangladesh Zailina 2013 Noodle fish VNR Hong Kong Noordiana 2011 Finfish, shellfish 0.38 to 15.7 μg/g Malaysia Goon 2014 Cod, salmon, tuna VNR Malaysia Goon 2014 Tuna, cod VNR Sri Lanka Joshi 2015 Rohu, mrigal 0.393 to 2.328 µg/g Nepal Zhang 2015 Squid 15.1-146 mg/kg China Sanyal 2017 Pangasius sp. VNR India Nayana 2018 Seer fish 0.704 mg % to 5.83 mg % India VNR=Value not reported.