SAU researchers make balanced animal feed from invasive sucker fish

In April 2025 a team of students, researchers and entrepreneurs at Sher-e-Bangla Agricultural University (SAU) in Dhaka reported that it had made a balanced, nutritious animal feed from the sucker fish, the armoured South American catfish that has spread through Bangladesh's rivers, ponds and haors and that the government banned in January 2023. According to a Jagonews24 report published on 20 April 2025, the team worked on the research for about a year, produced a feed for cats and other animals and completed field trials of it. The project was funded by IAAS World, the international association of agriculture students, and it placed fourth worldwide in the association's Global Project Competition 2024 under the theme "Producing animal feed from sucker fish".

In Bangladesh the sucker fish is widely seen as a harmful, worthless fish. Fishers and fish farmers blame it for torn nets, damaged pond dykes and smaller catches, and fisheries officials have called it a threat to native fish and to the environment. The SAU team's idea was to turn that problem into a resource: a fish that nobody wants could become a raw material, and if the catch has a buyer, removing the fish from the water becomes worthwhile.

The project was supervised by Professor Dr Kazi Ahsan Habib of the university's Faculty of Fisheries and Marine Science, Nazmus Sakib Anik, a lecturer in the Department of Fisheries Biology and Genetics, Professor Golam Mohammad Patwary of the Faculty of Animal Science and Veterinary Medicine, and lecturer Abdur Rahman Rafi, Jagonews24 reported.

Team member Niamul Islam, an SAU student, told the newspaper that alongside the familiar "waste to wealth" idea, the team had wanted to establish a "problem to wealth" theme, and to show how a problem such as the sucker fish could easily be turned into a resource. He said the feed achieved 70 per cent success in its first test and gave the hoped-for results in a second test. The report did not explain how that success rate was measured. Niamul Islam said the team hoped that if a commercial company marketed the feed, it would ease the pressure of animal feed imports.

Professor Habib said the feed made from sucker fish had been tested on cats and had given the expected results: the cats ate it. The team was working on further formulations so that the feed would also suit dogs and poultry. He said SAU was researching how to make feed for poultry, cats, dogs and other pets from the sucker fish, and that efforts were under way more broadly to make feed for poultry, fish and other animals from unconventional organic materials.

The Jagonews24 report did not publish the feed's nutrient analysis, the number of animals used in the trials or the way the fish was processed. The results described here are therefore those the research team reported to the newspaper on the date of the report.

Professor Habib told Jagonews24 that the sucker fish harms aquatic ecosystems and had by then spread from the Buriganga River in Dhaka as far as the haor region. Controlling it was badly needed but difficult, he said. If a commercial company took the feed to market, the university would for the time being have one way to help keep the fish in check.

The Buriganga, which Banglapedia describes as a tide-influenced river about 27 kilometres long running along the west and south of Dhaka, branches from the Dhaleshwari near Kalatia, receives the Turag at Kamrangirchar and rejoins the Dhaleshwari at Munshiganj. Its average width is about 400 metres and its average depth about 10 metres. Banglapedia records severe pollution, mainly from the tanneries of the Hazaribagh area, and notes that in the dry season the dissolved oxygen in the river falls to very low levels or to zero. Officials quoted by bdnews24 in 2022 said the sucker fish tolerates exactly such low-oxygen, polluted water.

The haors are, in Banglapedia's words, bowl-shaped tectonic depressions that become vast sheets of water in the monsoon and mostly dry out afterwards. They lie mainly in greater Sylhet and greater Mymensingh: the whole of Sunamganj district, much of Habiganj and parts of Sylhet Sadar and Moulvibazar. The basin holds about 47 major haors and some 6,300 beels, about 3,500 of them permanent and 2,800 seasonal, and Banglapedia calls the haors important fishing grounds of the country.

"Sucker fish" (sakar mach in Bengali) is the local name for armoured suckermouth catfishes of the genus Pterygoplichthys, in the family Loricariidae. They are native to Latin America and are sold around the world as aquarium fish. In a study published in the journal Aquatic Invasions in February 2024, Md Shakhawate Hossain of Bangabandhu Sheikh Mujibur Rahman Agricultural University and colleagues in the Czech Republic and Indonesia examined fish caught in the Turag River and in household ponds in Gazipur and Mymensingh and identified them as P. disjunctivus, P. pardalis or hybrids of the two. Earlier work used other names: the first scientific record from Bangladesh, published in 2008, named P. multiradiatus, and a bdnews24 report of November 2022 gave the name Hypostomus plecostomus.

The same study lists the traits that make these catfishes successful invaders: parental care and large eggs that produce strong hatchlings, nesting, long spawning seasons, high fecundity, rapid growth and a lifespan of more than five years. They can gulp air and take oxygen through the lining of the gut when the water is short of oxygen, and they can survive several hours of drying out in simple burrows. Their hard scales and the sharp spines on their fins deter predators.

The U.S. Geological Survey's fact sheet on the vermiculated sailfin catfish, P. disjunctivus, gives its native range as the Madeira River drainage of the Amazon basin and its size as up to 70 centimetres. The fish has flexible bony plates and a sucker-like mouth on the underside, forages on the bottom for detritus and algae, and can tolerate brackish water up to 10 parts per thousand for long periods. Males dig burrows in riverbanks, where females lay eggs that are then guarded, and burrowing in large numbers contributes to siltation and bank erosion.

The fish measured in Bangladesh for the 2024 study weighed 332 grams on average (90 to 540 grams) and had an average total length of 21.2 centimetres (17.8 to 26.2 centimetres). Fish described in newspaper reports ranged from 10 to 30 centimetres and from 0.2 to 2.0 kilograms. Local people know the fish by many names, among them "tiger fish", "thousand-spine fish", "helicopter fish" and "sucker fish".

In the bdnews24 report of November 2022, officials of the Department of Fisheries described how the fish feeds by sucking food with its mouth, eats the fry of native fish, competes with them for algae and small organisms, breeds quickly, tolerates low oxygen and polluted water, and can live for about 24 hours out of water. Officials also pointed out that it lives on the bottom, where heavy metals accumulate. Dr Md Khaled Konok, deputy director (fish culture) at the department, said that no country records it as a food fish.

According to the 2024 Aquatic Invasions study, Pterygoplichthys catfishes were imported into Bangladesh for the aquarium trade in the 1980s and escaped into the wild during the 1990s through both intentional and accidental releases. None was recorded in the wild until 2007, when the first was found in northern Bangladesh, a record published in the Journal of Applied Ichthyology in 2008. A review in the journal Fishes in February 2018 by Hossain and colleagues attributed the range expansion to aquarium releases and escapes from fish farms, made worse by dispersal during storm floods and through irrigation canals.

Before 2023 there was no law that banned imports of these fish, the 2024 study notes. Importing them required explicit permission from the Department of Fisheries, which treated them as a "conditional" species, but the authors described the rule as a dead letter, because aquarium traders were importing the fish and breeding them commercially in large numbers in local hatcheries without permission. Surplus fish from illegal breeding and connections with Indian rivers along the Ganges and the Brahmaputra during the monsoon are among the other routes the study suggests.

To map the spread, the researchers gathered newspaper reports and other accounts. They counted 65 records between 2014 and 2021 in 34 districts, covering about 200 fish caught by fishers or other people. Of the records, 69 per cent came from open waters such as rivers and floodplains and 31 per cent from culture or household ponds; the fewest were in 2014 and the most in 2020 and 2021. A climate-matching model indicated that almost all of Bangladesh suits the fish, with only parts of Satkhira, Sunamganj and the Chittagong Hill Tracts less favourable.

Another study, by Parvez and colleagues in the journal Biological Invasions in 2023, recorded the vermiculated sailfin catfish in 17 rivers across most of the country, with well-established breeding populations in four places. The researchers measured competition between the catfish and three native carps through growth, survival and gut analysis, and concluded that the invader affects these highly valued native fish.

In the November 2022 bdnews24 report, Khondaker Mahbubul Haque, then director general of the Department of Fisheries, said the fish had probably been brought in at some point to be kept in aquariums and had gradually spread to open water. The report said it first appeared in ponds and canals and then reached rivers, among them the Buriganga and the Halda, a major carp breeding river, and had entered fish enclosures (ghers), harming farmers. Dr Monzurul Kibria of the Halda River Research Laboratory at the University of Chittagong warned that a rapid rise in its numbers could threaten other fish and the wider ecosystem.

For the 2024 study, the researchers interviewed 97 people, among them fishers, fish farmers, fish sellers, pet shop owners, riverside workers and local residents. About half did not know the fish. Of those who did, most (63 per cent) were very worried about its presence in ponds and open waters and its effect on native fish production.

Every fisher interviewed on the Turag and Buriganga rivers said that the fish had damaged their fishing gear or that they had been hurt, or feared being hurt, by its spines; they also said fish catches had fallen in invaded waters. About 71 per cent of fish farmers agreed that the fish damages pond dykes by burrowing, makes the water muddy and reduces pond production. Farmers who tried to clear their ponds by draining and sun-drying them found that the fish came back; some believed dormant eggs in the mud were the reason. People who once bathed in the Buriganga told the researchers they were now afraid to, because the fish's hard spiny fins could injure them.

The authors also cite research showing that in invaded waters the fish take up much of the nitrogen and phosphorus and hold back the primary production on which other fish depend, and they point to the extra costs farmers face in repairing dykes and draining ponds. Most people who caught the fish threw them back into the water or onto the bank to die, and about 88 per cent of respondents suggested killing, burning or burying the fish once caught.

The fish arrived in waters already under pressure. The Red List of Bangladesh freshwater fishes published by IUCN Bangladesh in 2015 assessed 253 species and found 64 of them threatened: 9 critically endangered, 30 endangered and 25 vulnerable, Mongabay reported in October 2022. That report named habitat loss, overfishing, pollution and climate change as the main causes of the decline of native fish.

On 25 September 2022, the Ministry of Fisheries and Livestock published a draft proposal to amend the rules under the Protection and Conservation of Fish Act 1950 so as to ban the suckermouth catfish, and gave the public two months to send objections or suggestions. The final gazette notification, signed on 11 January 2023 by deputy secretary Mrinal Kanti Dey on the President's order, was made public on 25 January 2023, The Financial Express and The Daily Star reported. Under it, no one may import, culture, transport, sell, supply or keep the fish. bdnews24 later summarised the ban as covering import, breeding, farming, transport, sale, marketing, preservation, stocking and rearing.

In July 2023, at a press conference before National Fish Week, Fisheries and Livestock Minister Sheikh Md Rezaul Karim said the government would draw up a broad plan to eliminate the fish, which he described as a threat to the environment and to water bodies, bdnews24 reported. He said the government did not have the capacity to remove it from every river and urged public awareness. The 2024 study records that officials fished the Buriganga and publicly buried the fish they caught on the bank, to encourage people to do the same.

The ban stops trade in the fish but gives no use for the fish that are caught. Under the notification, transporting, selling and supplying sucker fish are prohibited, and the Jagonews24 report did not say how commercial production of the SAU feed would be arranged under that rule.

The idea of feeding sucker fish to animals had been raised in scientific work before the SAU announcement. In their 2024 study, Hossain and colleagues wrote that sucker fish raised free of pollution could be used to make fishmeal and poultry and cattle feed, citing earlier research, and that other researchers had suggested using the skin for handicrafts and body parts for soap, biofuel, enzymes, collagen or natural coagulants to clear muddy water.

In January 2025, researchers at the University of Phayao in Thailand published a study in the journal Life on replacing commercial fishmeal with meal made from P. pardalis in the diet of the Chinese bullfrog (Hoplobatrachus chinensis), a farmed frog. Over 90 days they compared six diets, from 0 to 100 per cent replacement, five of them with a plant extract added. The sucker fish meal had a better amino acid profile than the commercial fishmeal, in both quality and quantity, while the commercial fishmeal had more fatty acids. Growth fell significantly only in the group fed the full 100 per cent replacement, and liver enzymes did not differ among the diets. The authors concluded that the sucker fish meal could replace up to 75 per cent of commercial fishmeal in the frogs' feed without harming growth.

The same 2024 Bangladesh study adds a caution. It notes that contaminants from polluted rivers can build up in the fish's flesh, which is why it speaks of fish grown free of pollution, and bdnews24's 2022 report recorded officials' concern about heavy metals where the fish lives. The study also found that some homeless and very poor people collected the fish to eat or sold it on the street for about US$1.2 to 2.0 a kilogram, though about 70 per cent of respondents who knew the fish (34 of 49) refused to eat it because of its hard armour.

Sher-e-Bangla Agricultural University stands in Sher-e-Bangla Nagar in Dhaka. It began on 11 December 1938 as the Bengal Agricultural Institute, founded by A K Fazlul Huq, then chief minister of undivided Bengal; it was later renamed the East Pakistan Agricultural Institute and, after 1971, the Bangladesh Agricultural Institute. It became a university in 2001 under the Sher-e-Bangla Agricultural University Act. Its faculties include agriculture, agribusiness management, animal science and veterinary medicine, and fisheries, aquaculture and marine science, the last of them started in 2017, so the sucker fish project brought together two of its newer faculties.

IAAS, the International Association of Students in Agricultural and Related Sciences, was founded in 1957 in Tunisia and has its headquarters in Leuven, Belgium. It has committees in universities in more than 55 countries and aims to promote the exchange of knowledge, information and ideas among students. Its activities include seminars, exchange programmes and small development projects such as its Village Concept Projects, and on its website IAAS World describes itself as a student-led, non-profit organisation that connects agriculture students around the world.

Fish are central to food and jobs in Bangladesh. A Ministry of Fisheries and Livestock presentation of October 2024 put total fish production in 2022-23 at 4.91 million tonnes, said fish supplied 60 per cent of the animal protein people eat and gave per capita consumption as 67.8 grams a day. Citing the Bangladesh Bureau of Statistics, it said fisheries contributed 2.53 per cent of national GDP and 22.26 per cent of agricultural GDP in 2024, and it put full-time and part-time employment in the sector at 20 million.

The same presentation, citing FAO statistics for 2024, ranked Bangladesh second in the world for inland fish production and fifth for aquaculture, and it counted 260 freshwater fish species, 12 exotic species and 475 marine species in the country. It is this inland catch and pond production that the sucker fish threatens, through competition with native fish, damage to nets and dykes and the cost of trying to clear it out.

Photo: harum.koh / Wikimedia Commons (CC BY-SA 2.0)

Sources: Jagonews24, Aquatic Invasions (Hossain and others, 2024), Biological Invasions (Parvez and others, 2023), Fishes (Hossain and others, 2018), Journal of Applied Ichthyology (2008), U.S. Geological Survey, Life (University of Phayao, 2025), bdnews24, The Financial Express, The Daily Star, Banglapedia, Mongabay, Ministry of Fisheries and Livestock, IAAS World