The fish you eat possibly contains a cocktail of antibiotics, fed to it for reasons other than disease treatment, shows an investigation by Rajeshwari Sinha and Amit Khurana. They visit 22 fish farms in West Bengal to find out how rampant is the use of antibiotics and why it goes unnoticed
A fishy business
Forty-year-old Chandan Bera runs a freshwater fish farm in West Bengal’s Purba Medinipur district. He raises the state’s staple fish varieties, rui, mrigal and monosex tilapia, on his 80-hectare farm. Bera started cultivating fish on a small scale in 2002, but soon realised that more fish yields would bring more profits. Since then, protecting the health of his fish stock has become a priority. Bera mixes antibiotics such as tetracycline and oxytetracycline with fish feed to prevent and treat diseases. When Delhi-based non-profit Centre for Science and Environment (CSE) visited his farm in May, Bera was excited about his latest investment, a carton of enrofloxacin. “I was told this is a strong antibiotic. I will try using this as tetracycline is not selling much in the market nowadays,” he said. Enrofloxacin is a fluoroquinolone, a class of “critically important” antibiotic for humans and is not recommended for use in feed. Also, antibiotics are meant for disease treatment and not for non-therapeutic purposes such as mass disease prevention and growth promotion. But fish farmers like Bera are throwing caution to the wind.
West Bengal is India’s second largest fish-producing state after Andhra Pradesh and accounts for 16 per cent of the country’s total fish production. Of the 1.44 million tonnes of fish produced by West Bengal’s inland fisheries, 84 per cent of freshwater fish is cultivated. CSE visited six key fish- producing districts (see ‘Bengal in CSE spotlight’) and found rampant use of antibiotics in aquaculture, including for non- therapeutic purposes.
Tarapada Barman, another freshwater farm owner from the area, is a little careful while talking about his use of antibiotics. “We sometimes use terramycin [tetracycline] tablets when the fish show some infection,” he says. But CSE found bottles of amoxicillin and packets of cephalexin at the farm. More probing produced only a part admission from Tarapada’s son, Mohon, who is also a fish farmer. “Many kinds of medicines are used. We have grown up farming fish. We know what works best and when,” he says. Of the two antibiotics found, amoxicillin is used in the treatment of serious lung infections and is “critically important” for humans, according to the World Health Organization (WHO).
Antibiotics are added to the feed or pond water even when symptoms of infection or injury are seen in only a few fish. Debashish Halder, a state government fishery officer from Bardhaman, admits, “Antibiotics are indiscriminately used in freshwater aquaculture, especially in Hooghly and Bardhaman. Farmers use kanamycin and amoxicillin tablets at whim.”
Such indiscriminate use of antib iotics in aquaculture can cause bacteria to become resistant to the medicines over time, making common infections more difficult and expensive to treat in humans. Resistance to antibiotics is an emerging health concern and can lead to greater spread of infection, uncertainty in success of high-end surgical procedures and longer hospital stays. In India, high resistance is observed in treatment of prevalent infectious diseases like pneumonia, tuberculosis, urinary tract infection and infections of gut and bloodstream. (see ‘Hatching Superbugs’, Down To Earth, 1-15 August, 2014) Catch 'em young
Owners of freshwater hatcheries also routinely use antibiotics to prevent diseases in fish larvae. “We use 0.2-2.0 ppm amoxicillin in water on the second day in rohu, catla and mrigal larvae, meriquin [enrofloxacin] from the fourth to sixth day in catfish larvae,” says 45-year-old Raja Das (name changed), a hatchery owner in Naihati, North 24 Parganas. Antibiotic misuse in hatcheries starts well in advance. Parent fish in broodstock tanks are exposed to antibiotics for prevention against infections. Enrofloxacin and ampicillin are mixed with their feed which is packed in sacks and left to float in certain parts of the ponds. Sometimes, the antibiotic-laden feed is scattered manually in the water by farmers who go around the pond in small boats. “During the rainy season, when chances of infection are high, about three kg of antibiotics are added per acre (0.4 hectare) of broodstock pond area per month,” says Das.
At another hatchery in Mogra in Hooghly, preparations are on to initiate the day’s breeding process. Farmers separate mature male and female fish and carry them in bags to breeding tanks nearby.
The staff here denies using antibiotics despite bottles of augmentin and enrofloxacin being found on the premises. “We do not use antibiotics. They supplied something else in this bottle,” says a staff member, coughing up an explanation.
Et tu, shrimps?
While inland freshwater fish caters mainly to domestic consumption, shrimps reared in brackish water or saline water by fish farmers are largely meant for export. Tiger shrimp (Penaeus monodon) and white-legged shrimp (Penaeus vannamei) are two key varieties. Frozen shrimp is the “cash crop” of Indian fisheries and constituted 67 per cent of India’s total fish exports of Rs 33,441 crore in 2014-15. But they too have not been left untouched by antibiotics. Shrimps with antibiotic residues are now harming business interests.
In May this year, India recorded the highest number of rejections of its shrimp exports over the last 15 years. Rejected by the US Food and Drugs Administration, the shrimps were found to contain the banned antibiotics nitrofuran and chloramphenicol.
Similarly, about 17 export orders of shrimp were reported to con tain either furazolidone, nitrofurazone and chloramphenicol or excess oxytetracycline by European countries during 2012-15. Most of these are considered medically important and some are highly toxic. In India too, all are banned in shrimp culture except oxytetracycline. Since 2010, samples with antibiotic residues have increased over three times as per India’s internal residue control plan meant for exports.
The stakes are high. “Since shrimp exports fetch high prices, some farmers, especially in areas where scientific culture is practised, use antibiotics based on the understanding that it may keep their fish stock away from infection,” says Sailendra Nath Biswas, joint director of fisheries, West Bengal government. Fisheries scientist Manas Sinha from the Fishery Survey of India agrees. “There is voracious use of antibiotics in brackish water aquaculture because it is production oriented. However, farmers will never reveal what they are using.” Sinha is right. When CSE visited intensive shrimp farms in Hasnabad in North 24 Parganas and Contai in Purba Medinipur, farmers denied using any antibiotics. They said they followed the instructions of technologists from feed companies or sea-food export companies who visit their farms. A technologist from IFB Agro Industries Ltd, a company dealing in packaged marine foods, admitted to using antibiotics in shrimp culture. “We occasionally mix tetracycline or oxytetracycline with gut probiotics to prevent infections in shrimps,” he told CSE on condition of anonymity. There are only a few shrimp hatcheries in West Bengal and shrimp seeds are mostly obtained from Andhra Pradesh, Tamil Nadu or imported. Former fisheries scientist from the Indian Council of Agricultural Research, A Laxminarayana, says oxytetracycline and chloramphenicol are routinely added to tanks in hatcheries when the water is changed. “When given in the early stages of life, the antibiotics are metabolised out and do not occur in the final product. But there is a definite impact on the environment,” he says.
Inland freshwater aquaculture finds almost no attention in current Indian regulations. Though there are a few guidelines, these are limited to only a few species, such as tilapia. Moreover, the guidelines are not specific about antibiotic use.
Existing rules and guidelines cater mostly to export-oriented coastal aquaculture, which is brackish water culture. Hence, shrimp farming comes under the purview of the Guidelines for Coastal Aquaculture, Coastal Aquaculture Authority (CAA) Rules, 2005, which regulate antibiotic use. But the list of prohibited antibiotics is based on regulations in exporting countries and is not as per current trends of resistance and antibiotic use in India. Further, the maximum residue limit (MRL)—limit up to which antibiotic residues may be present—is set as “nil” for many other antibiotics. This allows for their use as long as residues remain undetected. It also does not recognise the issue of non-therapeutic use.
The Indian standards for fish feed by the Bureau of Indian Standards (BIS) and antibiotic residues in fish meat by the Food Safety and Standards Authority of India (FSSAI) are quite similar to CAA guidelines, banning only a select set of antibiotics and mentioning MRLs for only four. This allows for the use of a large number of other antibiotics in feed or otherwise. In addition, the BIS standards are voluntary and does not address feed premix. Thus, on-site addition of antibiotics to feed goes unchecked.
Over-the-counter (OTC) availability of antibiotics encourages their indiscriminate use by farmers. Pharmacists in the towns of Contai in Purba Medinipur and Kalna in Bardhaman admitted to selling terramycin capsules to farmers who transport larvae from hatcheries to farms. “Farmers follow the advice of other farmers and give human medicines to fish,” says a pharmacist from Naihati, a town in North 24 Parganas. “They think that if the medicines can work for humans, they will work for fish too.” He routinely sells cifran, azithromycin, terramycin and ampicillin to farmers. Drug control officers from West Bengal say they are aware that pharmacists sell antibiotics to farmers, but admit that the regulation mechanism to check this practice is lacking. “We do not have ample staff. Though there is regular inspection, it is not possible to control OTC sale completely,” says a drug inspector who does not wish to be named.
The use of veterinary grade antibio tics is not appropriate either. Farmers were found using medicines labelled for use in poultry or livestock, but not fish. These antibiotics are also cheaper and readily soluble, making them the go-to drugs for fish farmers. “We don’t know the names, but we use the medicines that are usually given to cows. They work well,” says a fish farmer from Moyna, Purba Medinipur. There is limited clarity on approved drugs for fish. The list of approved veterinary drugs provided by the Central Drug Standards Control Organization (CDSCO) makes no mention of fish. At the same time, there is no labelling for fish in medicines meant for veterinary use. When CSE asked CDSCO for clarification, it was asked to contact the Directorate of Drugs Control in West Bengal. The state Directorate, on its part, directed CSE back to CDSCO.
Farmers are unaware of the dosage of medicines or withdrawal period. While a farm owner in Sarberia, South 24 Parganas, says he mixes 10 g of terramycin per kg of feed, another freshwater farmer from Moyna, Purba Medinipur says, “We mix one gram of terramycin per kg of feed.” Workers at a hatchery in Kalna, Bardhaman, admit to sometimes adding even higher doses of antibiotics to the feed or water than those recommended by technical experts from companies for faster action.
No doctors for fish
There was no sign of professional disease management in aquaculture across the districts surveyed by CSE. Farmers, whose fish display signs of illness, rarely consult officers from the Department of Fisheries (DoF). Instead, they rely on the advice of their peers, big farmers or technical experts from companies. Dhrubajyoti Sen, a fishery officer in Hasnabad, says, “Although we have conducted so many trainings in the block, farmers do not come back to us. They ultimately do what they want.” But farmers say it is difficult to find fishery extension officers or fishery field assistants when needed.
A farmer in Hasnabad says, “There is only one fishery officer for a block of over 100,000 farmers. The officer is not always free for consultation.” Fishery officers are, however, not authorised to prescribe medicine for fish. And since veterinary officers in block offices do not cater to fishery-related issues, there are effectively no doctors for fish. The gap begins to form at the level of training itself. In India, fishery and veterinary science are taught as separate courses. While pharmacology—the science of drugs—is not dealt with sufficiently in the fishery science curriculum, veterinary science has little thrust on fisheries.
The routine use of antibiotics in fish is known to cause the emergence and spread of resistance. It can facilitate entry of antibiotic residues and resistant bacteria into humans and the environment through food, direct contact and farm waste. In the past decade, international studies have suggested that aquaculture can contribute to the spread of antibiotic resistance. In addition to India, resistant bacteria and genes have been isolated from fish and fish environment in many countries. Several nations and agencies like WHO, Food and Agriculture Organization and World Organization for Animal Health are working towards reducing animal antibiotic use.
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