Is it time to stop buying Puntius denisonii?

b1d057c9-41ac-455d-953f-761c338ec673

Editor's Picks
Features Post
The brightest pupils
04 October 2021
Features Post
Dealing with egg ‘fungus’
04 October 2021
Features Post
Rathbun’s tetra in the wild
13 September 2021
Fishkeeping News Post
Report: 2021 BKKS National Koi Show results
13 September 2021
Features Post
The World's forgotten fishes
16 August 2021


Matt Clarke speaks to Dr Rajeev Raghavan who is heading a research project to investigate the commercial fishing for Puntius denisonii and its close relative P. chalakkudiensis.

Few fishkeepers haven't heard of the Red-line torpedo barb, Puntius denisonii. It's one of the most colourful, classy and sought after barbs for the community tank, so it appeals as much to the connoisseur as it does to the new fishkeeper with a community tank.

However, such is the demand for this stunning species - which is reported to be India's most popular aquarium fish export - that it is now heading down the slippery slope towards extinction, due to over-collecting on a colossal scale.

Although described from the Indian State of Kerala by the British ichthyologist Francis Day in 1865, Puntius denisonii wasn't collected for the aquarium trade until 1996. However, it exploded in popularity almost immediately, after it won an award in the 'new species' category at Singapore's Aquarama exhibition in 1997.

Bizarrely, the species only took third prize, but it has gone on to become one of the industry's most consistently popular fish, holding its value much better than many other "new" fish with a typical retail price of at least a tenner – indeed prices may even have risen slightly recently due to demand exceeding supply. And its popularity shows no sign of waning.

The downward spiral
Nothing much was known about the conservation status of Puntius denisonii before collecting started in 1996-1997, but in the 12 or 13 years since it commenced, stocks have become rapidly depleted and the fish is now regarded by scientists as an endangered species.

However, despite this 'endangered' status, the trade in Puntius denisonii has continued at the same rate. Kerala's own fisheries department have actively promoted the trade in the species and other endemics in the apparent hope that the country could develop a commercial fishery as lucrative as that of Singapore's, and exporters have shipped the fish in their thousands.

There are currently no restrictions on the export, import or trade in the fish. It's not protected locally, it's not listed under the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES) and it's not mentioned in any of the previous IUCN Red Lists of Threatened Species.

However, studies made around 2000 reported that the abundance of the species in streams in Kerala varied from 'rare' to 'very rare' or 'untraceable', and by 2004 one study claimed that the population was declining at an annual rate of 70%. The situation has been deteriorating rapidly.

Vulnerable
According to Dr Rajeev Raghavan of the Conservation Research Group at Kerala's St. Albert's College Department of Aquaculture, who is a specialist on the denisonii fishery, the species is inherently vulnerable to fishing pressures, so it is perhaps little wonder that the massive exploitation of wild stocks have taken their toll on the species.

According to a recent study on denisonii by Raghavan and his co-workers, denisonii is found in nine rivers across Kerala, but has a distribution restricted to certain pockets and habitats within those rivers. As a result stocks are extremely fragmented.

The species is also gregarious and lives in large shoals in characteristic rocky pools lined with aquatic vegetation, so tracking down the fish and catching them isn't too challenging, and it's much more likely for over-collecting to decimate stocks locally.

“It is known that endemic species that present very restricted distribution ranges and small populations are especially vulnerable to extinctions”, said Raghavan. “The low abundance, gregarious aggregating nature, easy location of habitats and/or aggregating locations, together with an increasing market demand and popularity, make P. denisonii highly vulnerable to overfishing and possible endangerment.”

“The international trade in P. denisonii, as in the case of other aquarium fish, is more or less dependent on the collection and marketing of fry and early fingerlings (3-10cm), which have a vibrant colour pattern, unlike adults that are paler in appearance.

Fishing pressures

This leads to size-selective fishing and subsequent pressure on fingerlings. This high level of exploitation of juveniles, resulting in insufficient quantities left in the wild to reach spawning size, is certainly an area of much concern.”

According to a study by Radhakrishnan and Kurup, the species spawns in streams with the regional monsoons, with the eggs and fry being dispersed over wider areas by the food and nutrient rich flood waters. It's at this time, when the species enters different fishing grounds, that it's most heavily targeted, with collectors taking entire shoals. Raghavan says that most fishermen return the brooders back in the water, but believes the stress of capture could harm them and make them less likely to spawn.

There are no official records on exactly how many fish have been taken from the wild, but scientists have examined export invoices for denisonii shipped out of Kerala between 1996 and 2004. The rise was described as “alarming and predictable.”

Raghavan's team believes that denisonii prices have risen recently. They reckon that the increase in price is an indicator that the species is becoming more scarce in the wild.

“We believe that the gradual increase in demand for P. denisonii witnessed over the last few years has encouraged more catches from the wild, turning the stock position into a possible downward spiral. Yet another reason for the increasing market prices of P. denisonii could be the high mortality of the species during capture, transporation and captivity, thus leading to a reduction in the total number of individuals that reach the import destination/customer and subsequent market scarcity.”

Disputing the evidence
However, despite the extensive field work undertaken, some people have disputed the findings, with one reader even alleging that the studies were a ruse designed to inflate the market value of the species.

Manjunath Ananth, who works as a collector for the aquarium trade in India, told Practical Fishkeeping that he believes the report is flawed: “The experts have told only about Kerala state. The real fact is, the rivers which hold P. denisonii are also in neighbouring states, including Karnataka and Tamil Nadu. The rivers where the fish are found in Kerala enter the state from other countries.

“The numbers of fish caught in Kerala might have decreased, but recently large numbers have been found in other states which border Kerala in forest reserves where collection is prohibited. Being a migratory species, the fish are held due to the use of water for irrigation, the construction of dams and they are also used as food by locals in other states.”

Raghavan told Practical Fishkeeping that he'd also heard anecdotal reports from collectors that P. denisonii was being collected in Karnataka, however, he didn't find out until the papers were in press and didn't want to add what may have been potentially unreliable information to a paper published in a scientific journal.

Raghavan added: “Another chance is that the denisonii which Manjunath and others say are found in Karnataka and Tamil Nadu state could be a subspecies or even a different species – as is the case with P. denisonii and P. chalakudiensis. This would require molecular confirmation. If the news provided by Manjanuth is correct, then there is still hope for denisonii, especially since he has mentioned that the species occur mostly in protected areas of Karnataka and Tamil Nadu.”

'No conservation benefits' from captive-breeding'
You might think that the answer would simply be to breed this fish in captivity, as that would reduce pressure on wild stocks, and hopefully allow them to recover. Wouldn't it? After all, it's only a barb, and aquarium spawnings have been recorded. Many more difficult cyprinid species that have not yet bred in the aquarium are bred on farms in massive quantities with the aid of hormones. In addition, the consistently high demand and market value of the species would seem to suggest it would be a great choice for a profitable captive-breeding venture that might help take the pressure off wild stocks.

However, Raghavan's research team seem to be sceptical that captive-breeding will help much. They believe that the rationale of using captive breeding as a panacea for the conservation of threatened species is 'highly debatable.'

“Captive breeding as a conservation tool for endangered species can be detrimental if it induces economic competition. Technology for captive breeding of stream-dwelling fish such as P. denisonii requires a rather high level of investment and scientific expertise to succeed. In order to justify the initial expense of investing in the business of selling captive bred P. denisonii, traders may need to increase their sales. This in turn will lead to a situation where they compete for market share and resort to 'wild collection to supplement 'captive production' so as to meet an increased demand. Such an issue would have serious consequences especially when exporters launder illegally collected P. denisonii from the wild as captive produced fare.”

The in-situ solution
So if captive breeding is not the solution, what is? Raghavan told Practical Fishkeeping that banning the sale of the species wouldn't be good: “I feel that the best option is to manage the fishery at site level rather than asking the hobbyists to stop purchasing the species. P. denisonii happens to be the single major species on which the wild caught ornamental fishery from Kerala/Western Ghats is based on.

The collection and export of denisonii is now a major industry in the region and contributes to the livelihoods of many full time and part time fishers. Completely banning the sale of denisonii in the markets can therefore adversely impact local livelihoods in some way or the other.”

“Legal issues on ownership and harvest are poorly understood with regard to ornamental fisheries, and also freshwater fisheries in general. There are no specific fisheries acts or laws on freshwater or inland fisheries in the region. There is thus an immediate need for developing policies to manage ornamental fish collection and trade in Kerala.

“A few management measures we could suggest are 1) quotas, 2) licences and permits to fishers, and 3) Total Allowable Catch (TAC) limits. Also, since there are a few 'hotspots' from where large volumes of denisonii are collected, there should be policies for setting up no take zones. Another important strategy is 'temporal closure' during the monsoon, when the fish is known to breed in the streams of Kerala.”

Raghavan says he's not sure when such management plans could be implemented, if ever, as he believes government agencies still don't understand the complexity of the issue. Before anything can be done, detailed studies need to be made to assess the stock structures of the denisonii fishery, so management processes can be built around them. Raghavan says that Indian government agencies and organisations have displayed a “thoughtless attitude in actively promoting the trade in native ornamentals and urging locals to do more, so as to cash in on the current boom in tropical fish exports.”

Getting the species on the IUCN Red List of Threatened Species might help make people realise that the fish was vulnerable. However, it doesn't impose any trade restrictions and a sizeable number of species listed are still traded. For that, the species needs to be listed on by CITES. However, if that happens, it's going to be a relatively long way off, as there's an arduous process to go through in order for the restrictions to be granted.

Thankfully, the list of species that have been placed under threat as a direct result of the aquarium trade is very small. Let's hope that the local and international agencies involved introduce some form of control to prevent this problem from escalating further. In the mean time, we still think it's worth thinking carefully about the ethics of purchasing wild denisonii.

Further reading

  • Dennick, V (2008) – How to breed Puntius denisonii, Practical Fishkeeping magazine. June 2008.
  • Clarke, M (2004) - Red line torpedo barb, Puntius denisonii. Practical Fishkeeping Online.
  • Clarke, M (2005) – Puntius denisonii tops Kerala's exports. Practical Fishkeeping Online.
  • Clarke, M (2007) – Video: Tank-bred Puntius denisonii. Practical Fishkeeping Online.
  • Clarke, M (2008) – Puntius denisonii threatened by aquarium trade. Practical Fishkeeping Online.
  • Raghavan R, Prasad G, Pereira B, Anvar Ali PH and L Sujarittanonta (2008) – 'Damsel in distress' – The tale of Miss Kerala, Puntius denisonii (Day), an endemic and endangered cyprinid of the Western Ghats biodiversity hotspot (South India). Aquatic Conservation: Marine and Freshwater Ecosystems. DOI: 10.1002/aqc.963.
  • Prasad G, Anvar Ali PH and R Raghavan (2008) – Threatened fishes of the world: Puntius denisonii (Day 1865) (Cyprinidae). Environmental Biology of Fishes (2008) 83: 189-190.

This item was first published in Practical Fishkeeping magazine in 2008 following an exclusive interview with Dr Raghavan.