Giant catfishes of Bangladesh: Fated to live in stories only?

Now, it is monsoon in Bangladesh.

With monsoon, there comes torrential downpour. Incessant rains, in turn, magnify the 700 rivers that flow through the country.

During monsoon, the whole country – the largest delta on the planet – often appears as one big flooded landmass.

River and rain make a happy combination for fishes. So, I started leafing through a book by Jeremy Wade, the legendary angler best known for the TV show "River Monsters."

Field memoirs of Jeremy are as unputdownable and nail-biting as his shows. Of his many encounters with the fish giants described in "River Monsters: True Stories of the Ones that Didn't Get Away," I was reading his plight of catching goonch catfish (Bagarius yarrelli) from a gorged rapid of India's Uttarakhand.

Goonch catfish is found in our rivers; in Bangla, we call them Baghayr. This fish can get an enormous dimension. The largest of its kind is caught here in this time of the year.

It is said that they follow downcurrent to breed. But we do not know much about them.

So, I picked a volume of "Encyclopaedia of Flora and Fauna of Bangladesh" and counted how many catfish species of Bangladesh can cross 6 feet in length. After a good digging, I found seven names and about 10 species.

Then, I drew another book: "Red List of Bangladesh" by the IUCN (International Union for the Conservation of Nature).

And I found every one of them marked as "Threatened." Rivers, rain and monsoon might keep these giants going. But, for how long?

Today's issue of The Business Standard Earth pays a tribute to our gigantic catfishes.

What's in the name?

A catfish, big or small, is nowhere close to a cat. Yet, we liken a catfish to a cat because of the "cat-whisker" a catfish generally possesses in front part of the mouth. The whiskers, under appropriate terminology, are called barbels.

However, Siluriformes – the order of catfishes – is a diverse one. Of every 20 vertebrate species, there will be a catfish.

Many, in evolutionary response, have lost their barbels. The number of barbels, when present, can vary from a simple neat pair to a beard-like aggregation.

Catfishes are generally bottom dwellers. However, a few, like yellow-tail catfish (Pangas) and giant wallago (Boal), live in the upper column of water.

Catfishes have no scales, but some can be covered with bony plates. As their flesh is boneless, the large ones are prized delicacies.     

Bangladesh is rich in catfishes. A handsome part of our freshwater fish diversity is composed of this group. All major Asian families live in our water bodies.  

Asian shovelnose catfishes

These catfishes readily stand out for their flat, shovel-like muzzle.

Two independent groups of shovelnose catfishes have evolved: One is the sorubim catfishes in the Amazon and the other is Ayr in South and Southeast Asia.

Two different types of Ayr are common in our waters. We can differentiate by their muzzle length.

Sperata aor has a visibly shorter "shovel" than Sperata seenghala. Ayrs are bottom-dwelling predators and need heavily oxygenated water.  

Both of our Ayrs are "vulnerable." However, they have successfully bred in captivity in facilities of the Bangladesh Fisheries Research Institute.

A third species named Sperata aorella is reported, from Kolkata, by a 2010 Zootaxa work but was never recorded from Bangladesh.

Two giants of our estuaries

Whale catfish (Rita) and eel-tail catfish (Kain Magur) rule our estuarine waters.

Rita exhibits a unique behavioural act. This fish swims upriver to breed in monsoon.

Young Rita comprises handsome yield of every fish-landing station of the Lower Ganges. But overfishing of immature Rita comes with a great cost.

The fish can cross the 6-feet mark; however, the large ones are fast disappearing. Rita is Endangered in Bangladesh.

Kain Magur is a master of the mangrove waters. This fish is armed with venomous stings on dorsal and pectoral fins.

If not handled with care, this fish can inflict a severe wound. The larger the specimen, the greater is the delivery of venom.

However, the Kain Magur venom is strong but heat-labile. The largest recorded size of Kain Magur is 5.9 feet. This species is Near Threatened.

Pangas of our large rivers

We call this fish Pangas both in Bengali and English. Due to the advent of aquaculture, Pangas forms a bulk of our yearly fish consumption. But, that is not all about it.

There is one Pangas that lives in the rivers. We often call it Nodir Pangas (Pangas from a river).  It is a widely sought after fish which is bigger and tastier than the farmed ones.

And farmed Pangas is a different species which is genetically modified in certain cases.

Nodir Pangas (Pangasius pangasius) is Endangered in Bangladesh. Overfishing summons the demise of our riverine Pangas. The wild stock is being frequently hybridised, thanks to the spread of cultured specimens.  

A faded giant of northeastern rivers

In Sylhet region, silond catfish (Shillong) is a popular and expensive food fish. When there is a good harvest, it also reaches Dhaka city.

According to descriptions of Francis Day and Francis Buchanan-Hamilton, two eminent ichthyologists whose work shaped ichthyology of the Indian subcontinent, silond catfish can attain 72 inches in total length.

This species might enjoy the safest status in Bangladesh where it is a Least Concern species.

But all the specimens we generally see are not decent in size, maximum staying between 2-3 feet.

Does anyone of us know when a 6 0r 5-feet silond catfish was caught in Bangladesh waters last?

The title contenders

When it comes to the big catfishes of Bangladesh, the second place goes to Boal.

Giant wallago is a fish of upper water column which prefers well-vegetated flood plains and haor basins than open rivers. It is predacious. But how aggressive they are?

I used to have a specimen in my aquarium. At one point, it managed to eat another fish more than half of its body size.

However, Boal is Vulnerable in Bangladesh, and Near Threatened globally.

King of kings

And the title goes to goonch catfishes. They are creatures of water bottom. Their black stripes on the brownish body give them a tiger-stripe pattern, an aid to camouflage.

From June to September every year, gigantic specimens weighing more than 300 pounds are caught from the Brahmaputra, the Surma and the Kushiara rivers. And, they become national news.

Nobody knows how and why goonches this big get into our rivers. It is said that they come downstream to breed, but there is no concrete evidence of this.

Goonch catfishes are one of the least-studied fishes of our delta. This species is Critically Endangered in our country.

They were once termed "vermin of water" during the British Colonial periods. Goonch catfishes were not even taken as food then.

Now, they have become "underwater Yeti" as dubbed by Jeremy and the 6-feet specimens have a market value of over $2,000.

And what is the least-discovered animal group of Bangladesh? The straight answer will be fishes.

When I look at the map of Bangladesh, I wonder how our rivers resemble veins and arteries of a human body.

I try to fathom the might of the Teesta and the Brahmaputra when they step into Bangladesh from the north. My eyes get fixed on the Ganges and her merger with the Brahmaputra.

Looking at the northeast, I find two rapid rivers: the Surma and the Kushiara. On the downstream, they form the Meghna; on further south, I see the greatest river confluence of the earth.

Looking at the mangrove estuaries and nearly impassable hilly rivers (the Sangu and the Mahamuhuri), I recite the fact: No fish expedition has been made to these places in contemporary times.

And I feel the zeal of an expeditor shivering down my spine.

But how our gigantic catfishes are connected to these glimmering facts?

"The day the last monster dies is the day the river dies too," Jeremy ends his book with a stark reminder.

GIGANTIC CATFISHES AROUND THE WORLD

Enormous catfishes always attract master anglers. From logbooks and field stories, we found claims of specimens reaching nearly 10 feet or even more. Mekong giant river catfish, Piraiba and Wels catfish are three species that are present in these fable-like descriptions.