- A recent study in Bangladesh reveals high rates of antibiotic resistance in pabda fish (Ompok pabda) bred by farmers through aquaculture.
- Consumption of antibiotic-resistant pabda fish may lead to the development of antibiotic resistance in humans as it exposes the food chain to multi-drug resistant (MDR) bacteria.
- Pabda aquaculture in Bangladesh produces around 20,000 metric tons annually, some of which is exported.
- Researchers are advocating educating farmers on the correct usage of antibiotics with the intervention of fisheries experts.
DHAKA, Bangladesh — Mohammad Monir, a fish vendor from Khilgaon in Dhaka, Bangladesh’s capital, was arranging a new batch of pabda fish (Ompok pabda) in his tray. Due to the high demand for the fish, his first batch had sold out quickly. Every evening, he manages to sell nearly 20 kilograms (44 pounds) of pabda.
“Pabda fish is delicious and costs comparatively less than other appetizing fish, at $2.5 (300 takas) to $4.18 (500 takas) per kilogram, depending on the quality and supply,” Monir said. “We have two more of outlets adjacent to this one. In total, we sell around 60 kg (132 lb) of pabda every day.”
Another vendor named Mohammad Shahin was selling the fish at $2.1 (250 takas) per kg. Several customers queued at his store as he was offering a cheaper rate. “I sell over 15 kg per day on average,” Shahin said.
Other vendors in the evening fish market shared similar experiences. Because pabda fish is abundantly produced in the country’s aquaculture industry, its prices remain relatively affordable in line with the rising demand.
Food prices have been soaring in Bangladesh, with food inflation exceeding 10% for some time now. It even reached 14.1% in July. As a result, any fish that remains affordable for the middle class sees high demand.
However, a recent study published in ScienceDirect has revealed high rates of antibiotic resistance in pabda fish. The study found particularly high resistance frequencies to antibiotics such as trimethoprim (95%), sulfafurazole (75%), ampicillin (60%), amoxicillin-clavulanic acid (55%) and cephradine (50%) in pabda fish.
The study also found that the overuse of antibiotics in Bangladesh’s aquaculture system is spreading antibiotic-resistant genes into the environment, which is posing significant health risks to consumers by exposing the food chain to multi-drug-resistant (MDR) bacteria.
Afrina Haque, a faculty member in Jahangirnagar University’s zoology department, who led the study, told Mongabay that their research confirms the unnecessary use of antibiotics by aquaculture farmers in Bangladesh. The team collected pabda fish samples from the aquaculture systems because of the fish’s high market demand.
Pabda aquaculture covers approximately 1,500 hectares (3,700 acres), with an annual production of around 20,000 metric tons, according to Moshiur Rahman, a senior scientific officer at Bangladesh Fisheries Research Institute (BFRI).
Pabda fish are also harvested from Bangladesh’s natural water bodies, including rivers, haors (large wetlands) and beels (smaller lakes), with around 1,000 metric tons collected from these sources.
“The demand for pabda is very high in the market due to its taste, a desired fat content and a lack of intermuscular bones. Farmers are keen to culture this fish because of its high market demand and higher profits. Besides, the culture period for pabda is much shorter than that for carp or pangas,” Rahman told Mongabay.
To analyze the bacterial community in pabda aquaculture settings and examine how bacteria persist in the culture environment, the researchers isolated bacteria from the gills and guts of the fish. They also collected samples from the water and sediment in the pond.
“To understand the diversity of bacterial types, we selected 20 colonies for sequencing and conducted molecular identification to pinpoint the specific bacteria present in the samples. Following this, we investigated whether these bacteria were pathogenic or beneficial. Most bacteria were identified as pathogenic, some of which have previously been found in poultry,” Haque said.
Unregulated antibiotic doses and health risks
Molecular identification revealed that many of these bacteria were antibiotic-resistant, with some exhibiting extensive drug resistance.
“We wanted to investigate how multidrug-resistant bacteria support biofilm production. Some studies indicate that certain bacteria support biofilm formation, while others do not. In our research, we found out that the bacteria were not producing biofilms pathogenically — proving that our farmers use antibiotics unnecessarily,” Haque said.
The researchers also noted that different fertilizers used in the surrounding croplands are carried by rain and runoff into the ponds where the fish are cultivated.
Besides, Haque said, farmers often use antibacterial medicine to boost fish growth, mixing antibiotics into fish feed to prevent diseases. However, what they may not realize is that this practice contributes to making the fish antibiotic-resistant.
“As consumers, when we eat fish containing antibiotic-resistant bacteria, we can develop the same resistance. In some countries, people consume raw fish, increasing the risk of ingesting these harmful bacteria directly. And our fish is exported too,” Haque said.
“So, our aquaculture farmers should be warned that antibiotics should not be used indiscriminately. They should consult the fisheries experts to determine the correct dosage and avoid overusing them,” she added.
Aquaculture’s growing impact in Bangladesh
Bangladeshis are known for their traditional fish-based diet. Against a total fish demand of 4.2 million tons, the country produces 4.7 million tons of fish. And aquaculture plays a crucial role in Bangladesh’s overall fish production.
Of this, 1.3 million tons are captured from open water, and around 7 tons come from marine fisheries, and the remaining 2.7 million tons are produced through aquaculture. Bangladesh also exports 74,042 tons of fish, contributing approximately 1.05% to its export earnings.
Rahman said that farmed fish contribute 58% to Bangladesh’s total fish production, while fish from open water accounts for 28%.
Pabda’s contribution to the country’s total fish demand remains modest at around 0.5%. However, Rahman noted that since the development of the first breeding technique in 2002 and the start of its cultivation in 2011-12, pabda cultivation has shown steady growth, particularly from 2014-15 onwards.
“Previously, pabda cultivation was limited to Mymensingh region, but it is now spreading across the country and continues to grow steadily,” Rahman said.
Hygiene question in aquacultures
The researchers and experts emphasize that aquaculture farmers in Bangladesh need proper hygiene guidance to produce fish free of antibiotic resistance.
Haque said they found certain bacteria linked to diarrhea, which could potentially have entered the pond through human or animal waste. “It shows the importance of educating farmers about proper waste management, hygiene and pond maintenance,” she said.
“Additionally, fertilization practices in nearby fields should be managed to prevent pond water contamination. When fields are adjacent to aquaculture ponds, careful application of fertilizers and pesticides is crucial to avoid runoff contamination,” she added.
Rahman also highlighted the growing concern of antibiotic resistance in Bangladesh’s aquaculture sector, “especially veterinary antibiotics, without consulting the specialists.”
“As a result, consuming this fish may contribute to antibiotic resistance in the human body. We should take immediate measures to control antibiotic use in aquaculture farms, and concerned fisheries officers should be involved in any antibiotic treatment on these farms,” he added.
Banner image: Fishers catch fish in a net in their aquaculture enclosure. Image by WorldFish via Flickr (CC BY-NC-ND 2.0).
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Citation:
Haque, A., Chowdhury, A., Bhuiyan, M. N. I., Bhowmik, B., Afrin, S., Sarkar, R., & Haque, M. M. (2024). Molecular characterization, antibiotic resistant pattern and biofilm forming potentiality of bacterial community associated with Ompok pabda fish farming in southwestern Bangladesh. Microbial Pathogenesis, 194, 106818 doi:10.1016/j.micpath.2024.106818