PFK in Sri Lanka: Rainforest streams


Jeremy Gay continues his expedition of Sri Lanka, where things just get better and better...

Our rainforest stream expedition took us to Boralugoda and we met our guide Shantha Jayaweera, president of the Organisation for Aquatic Resource Management (OARM).

Shantha knew this area like the back of his hand and had also been involved in conservation work, planting some 30,000 trees to restore the natural habitat.

He explained that the area we would be exploring had the highest freshwater fish diversity in all Sri Lanka, but it had also been at risk from human activity, including sand mining for construction in the main river and deforestation which affected the streams.

The Sri Lankan government had previously given the land to the people for farming, but, aware of potential biodiversity loss, OARM recorded the many species there and advised the government of potential damage.

They cited sand minding and farming, as deforestation caused soil erosion. Even tractor tracks acted as slipways for soil-laden water to run straight into what should be clear water streams and important habitats.

Deforestation was stopped, and Shantha and OARM have been working in the area ever since.

Pool of surprises

After meeting some locals at the OARM office on the first day of this expedition, we made for the hills. Our vehicle was a Tuc Tuc and we wondered whether it would cope on some pretty steep dirt tracks.

We pulled over next to a stream which ran down a heavily vegetated gully by the roadside. Looking down through trees and ferns we could see a pool, about 2.4m/8’ round and fed by a tiny stream. This, said Shantha, was the habitat of Cherry barbs.

As we descended to the stream (pictured above) I could see that the pool was man made, or man modified, for bathing. A large rounded stone stood at one side, with traces of soap suds on top, and the pool had been dammed at one end with sacking to maintain a depth of some 30cm/12”.

Someone was using the spot for bathing and washing clothes, though, when they weren’t around, the fish used the pool too!

We set to work with four hand nets and were soon catching fish: Giant danios, Devario malabaricus, beautifully coloured Combtail paradise fish (pictured above) and, from the corner of the pool, Cherry barbs. I was happy indeed!

As we netted some of the barbs one crimson male continued about his business, toing and froing from behind a large stone, displaying to females and subordinate males. Yet this pool was wider and deeper than normal and the stream proper was just inches deep and two to three feet wide. It was so shallow that many rounded stones and pebbles in the stream bed were sticking out of the water.

You wouldn’t find fish that small in UK hill streams. They wouldn’t be able to negotiate the obstacles on the way there either. Yet here in Sri Lanka, in possibly the most beautiful stream habitat found to date, were those little beauties.

Shantha’s helpers went upstream and started to return with some small snakeheads. Shantha explained that both Channa gachua (pictured above) and Channa orientalis lived in the habitat and soon we had both species in our photo tank.

I thought I kept Channa orientalis some years ago and was proud of the fact — only to later find out that they were more than likely the more common Channa gachua. I had also obtained them from a supplier in India, yet Shantha confirmed that true orientalis only came from Sri Lanka.

In size, shape and colour the juveniles looked similar. Only a close inspection of the underside reveals the total lack of pelvic fins on true C. orientalis.

Shantha promised me a larger, adult specimen which he would catch at night by torchlight.

I studied the habitat and puzzled over the fish species living there. In this tiny stream were Cherry barbs, but then bizarrely there had been Giant danios — a fish I had seen the previous day in streams much larger and flatter. When the paradise fish would be fully grown they must have their backs sticking out of the shallow water. Then there were those two snakehead species living sympatrically…

The habitat gave me clues as to how snakeheads should be kept in captivity and why they do what they do — like jump, escape, and fight each other.

In this environment these agile air breathers had to be virtually amphibious to navigate the stream, sliding over stones and riffles, and jumping over dams and other obstacles. In the wet season they could probably travel over land too.

Although they lived in the same tiny habitat they certainly weren’t living together — each fish spaced some 5m/16’ apart along the length of the stream. These fish hunt as loners and suspected diet is shrimp, insect larvae and small fish.

Place these truly wild creatures in a brightly lit, glass box in full view and in close proximity to each other and you will get fighting and escapees. They are much better in low stocking densities, in long shallow tanks with lots of hiding places, as nature intended.

If with unlimited resources I would keep them in a mega paludarium, just inches deep in water but many feet in length and filled with terrestrial vegetation above the waterline and sealed with glass sliding doors at the front to trap in humidity.

That way if the Channa did feel like walking they could do so — and not be discovered dried out on the carpet the next day. You could even feed crickets and the like too.

In the small stream we also found Banded mountain loach — with the two we caught having very different patterns.

Feeling chuffed to have been to the natural habitat of yet more of my favourite fish, I talked more with Shantha about the Channa as he shared my passion, creating some outstanding paintings of them.

He explained that snakeheads are extremely important to the local human populations as the young eat mosquito larvae. He added that adult snakeheads are also an important source of protein, being offered to emaciated people and pregnant women.

He added that they successfully defend their young and are great parents, though once babies leave their parents’ care they are predated by the larger specimens of their own species, so effectively controlling numbers.

The eventual haul from our short time at the stream included freshwater crabs and Clarias catfish, and water tests revealed a temperature of 26°C/79°F, pH 6.8, GH3 and KH6. The stream’s name was Cos Dola, meaning 'Jack fruit stream.' Fruitful it certainly was!

War movie scene

Later that day Shantha took us to the Maguru river (pictured above) hidden by rainforest vegetation. A hike got us there, travelling through hillside tea plantations and low-level rice paddies, with the paddies and surrounding hills resembling a Vietnam war movie.

We scanned the water bodies as we travelled, Shantha pointing out yet more snakeheads in ditches surrounding the paddies.  

Ever on the lookout for aquatic plants, I spotted what looked like Blyxa growing in the corner of one of the paddies. Puntius bimaculatus were in the ditches and paddies.

After a scary descent through steep forested hills to the river, the scene opened onto yet another beautiful vista.

This was the Maguru Ganga cutting its way through the hills and looking fantastic in early evening sunshine.

The habitat was rocky with huge boulders and a waterfall at the head of the river. The water was deep and clear, over 180cm/6’ in places, and lined with smaller boulders, along with patches of clean quartz sand.

Water tests showed a temperature of 27°C/81°F, pH 7.2, 3GH and 6KH. We donned swimming gear and got in.

It was there that I had what Peter Richardson of the Marine Conservation Society (MCS) called my Zen moment. He knew what that meant and had recommended this trip for just such an experience.

The greater depth meant that we could go 'proper' snorkelling and I spent some 20 minutes at a time just following fish. The underwater landscape was dramatic with huge striated rocks opening up to large expanses of deep, open water.

It was so clear that 10m/33’ or so of water could be viewed ahead, so you could make out points of interest and explore.

Fish were there, but sporadic and low in number. I swam thinking just how lucky these residents were to live in this pristine river, largely cut off and protected from the outside world. The three by now usual suspects were there: Puntius singhala, Black ruby barbs and Rasbora daniconius (pictured above) — with the rubies confirming that they clung to rocky cover in the margins and hung around in low numbers.

R. daniconius were definite shallow water fish and the singhala, larger and fish of open water.

River of walking catfish

The stars however were the large Garra ceylonensis (above) that swam in groups of five or so from rock to rock and paraded some 50m/164’ of river. Named the Maguru river, or river of the walking catfish, it appears that the Garra is king.

The huge boulders and clear, well oxygenated water offered excellent grazing for these fish and I could see the tubercles on the heads of mature fish.

In such a paradise I puzzled over why it wasn’t more heavily populated and by larger fish in larger numbers. The Garra and Singhala barbs did seem nervous. Shantha told me that Tor khudree, the mighty mahseer, was also in these waters —a threat confirmed by Shantha’s keen eye for wildlife, spotting fresh otter spraint on rocks nearby. They too were here.

Another highlight was getting to properly observe the goby species. I could swim from deep water to a sandy channel between rocks and directly over freshwater gobies going about their daily business.

The Awaous melanocephalus were busy sifting the quartz sand, whereas the Redneck gobies and Lipstick gobies (pictured above) were more rock bound. I hovered next to a submerged boulder. In front a Lipstick goby clung to the vertical, striated rock face, looking more like something from the ocean than freshwater river.  

Our guides’ assistants also found a large spiny eel jammed into a rock crevice, just with its head pointing out. It obviously felt quite safe as it stared back at me.

A habitat interpretation of this river in an aquarium would look more like a Malawi or Tanganyikan biotope in terms of the huge rock structures, only with riverine fish. Again I was learning as I swam, determining exactly why Garra can be so territorial in the aquarium.

These grazed an area the size of an Olympic swimming pool with no competition, so an over populated aquarium must seem claustrophobic at the very least and unliveable at worst.

The next day was to be the last of our trip and we travelled further down the Maguru to where it became wider, flatter and much more sandy. Here the river was some 25m/82’ wide but only about 60cm/ 24” deep at most.

Vast sand banks and water worn, sunken wood were everywhere. Shantha said that this was where a lot of the sand had been excavated for house construction, but this practice had now largely stopped.

I waded across the river and headed for a small tributary to the main river on the opposite side. Averaging 1.8m/6’ across and 45cm/18” deep, this stream felt cooler than the main river, being shaded by overhanging vegetation and steep banks rising and creating a kind of cove that meandered and disappeared into the forest.

The clear water flowed over mud, sand, wood and leaves and I followed Black rubies around the corner, catching a small needlefish, Xenentodon cancila, as I went.

Special moment

This was to be a special moment as I headed upstream at one with nature. Being as quiet as I could, I could see fish around every bend of the stream. I saw beautiful Belontia signata with crimson red tails along with Rasbora daniconius before stopping to watch the best Black ruby barbs I had yet seen. They were totally unaware of me.

I saw fry in the water below, moved the net through them and was delighted to see they weren’t fry but the elusive Fire rasbora, Rasbora vaterifloris (above). This Sri Lankan endemic is still quite rare in the hobby and is said to come in several naturally occurring colour morphs.

These looked orange, though Shantha said that five colour morphs could also be found.

Stood in the stream in my own silent bliss I saw Cummings barbs, though couldn’t catch them during my first few attempts. Further upstream it became shallower and divided by fallen branches. I saw a larger needlefish — there I suspect to predate the vaterifloris — more Cumming’s barbs, a plain barb with a red dorsal fin, Puntius dorsalis, and some larger, redder vaterifloris.  

We rested the photo tank on what Shantha told me was a 300-400-year-old fallen tree used by generations of villagers as a bridge. In the main river I watched gobies and spiny eels as Shantha told me there were actually two Cumming’s barbs species: the true Puntius cummingi we had caught were known as the Lemon fin, whereas the one we know in the trade with orange fins is actually Puntius reval.

He also explained that spiny eels were trapped in bamboo poles and eaten by the locals.

Downriver was a large pool said to contain Channa ara — a large snakehead species now rare in the area. Correctly named Channa marulia, there is said to be a monster-sized specimen living in the bottom of a well in a nearby village.

Other fish species included Spotted loach in the tributaries, Asian stinging catfish and a few fish I checked out with Sri Lankan ichthyologist Rohan Pethiyagoda as they seemed of interest.

We found Laubuca further up the tributary, living sympatrically with Devario malabaricus. It was the first time that we had found these. When I read one of Pethiyagoda’s scientific papers I wondered if we had caught the new Puntius kelumi, and Labeo lankae as well.

All in all the Sri Lanka adventure had been amazing trip, giving me a unique chance to see some popular aquarium fish doing what they do best — living wild!

Still discovering, even back home...

Shantha Jayaweera was so good at collecting fish that it wasn’t until I returned to the UK that we got a good look at all the pictures of our catches.

We sent the pictures to Rohan Pethiyagoda and he identified a Mystus catfish I caught as Mystus ancutta, a newly described species. and confirmed that the different looking 'daniconius' we caught in the Maguru weren’t R. wilpita, but that he had just submitted a paper on them and that names may well be set to change.

He also identified the eel pictured above as Mastacembelus cf. armatus

Thanks to Rohan for his expert identification.

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