Do go chasing waterfalls


As Jeff Goldblum famously says in Jurassic Park, ‘life finds a way.’ As Tai Strietman explores some inhospitable habitats, he realises how true that is.

Sometimes you look at a habitat and think ‘fish would hate this place.’ You’d probably be wrong and your assumption might be based on our very human perspective of the natural world; the spot may be muddy, murky, extremely fast flowing, terribly loud due to crashing water, full of detritus — there are so many things that we might assume make somewhere uncomfortable to live, but for fish, it might just be the perfect place to call home.

A trip to a fast-flowing river in Central-West Brazil, led by catfish expert Luiz Tencatt, saw me encounter just such a habitat, although first we had a long drive ahead of us. After heading north from Campo Grande, in the state of Mato Grosso do Sul, we spent several days exploring the region around the town of Coxim, home
to the famous Black Neon Tetra, Hyphessobrycon herbertaxelrodi. On our last day, Luiz took us to a ‘secret spot’ east of the town where he had been conducting research and collections with his team from the local university, but which was apparently unknown to the public. 

To get there, we drove for hours through great oceans of soy stretching to the horizon and beyond, broken every now and then by wide plantations of eucalyptus, sterile growth destined to become paper and charcoal. Here are there, tiny islands of indigenous forest remained, their tall trees and dense undergrowth lapped at by the waves of monoculture crops. 

The entire region was formerly a dense patchwork of woodlands and savannah, with corridor forests once running alongside waterways now choked with pesticides and fertiliser runoff, and cleared of any accompanying trees. 

The wrong greenery

Soy is used in many food products and is, ironically, a critical ingredient in many vegan foods. Of course, there are alternatives to soy and many vegans actively search for them, but I found myself wondering if the ‘out of sight, out of mind’ mega-agricultural industry of soy was laughing behind the backs of those hoping to rescue the natural world and be ethical by making dietary choices to achieve this. In terms of biodiversity, put simply, there was none. We saw only one species, the Giant Rhea, a flightless bird like an Emu. They are one of the few beneficiaries of agriculture, to an extent, as they move in bands picking up seeds from the tilled earth. Usually on long drives, one would have to keep an eye out for crossing armadillos, crab-eating foxes, ocelots, snakes, large lizards, tortoises, rodents, deer and Giant and Southern anteaters. We saw none of these. Even the usual avian scavengers that soared above or sat by the side of the highway were absent, there was no roadkill to eat because almost nothing could live here anyway. 
While looking out across the sea  of monotonous green with its small islands of trees dotted here and there, I reflected that the reason I was so upset by the scene was because I knew what it should look like. I have explored areas where such cerrado (savannah and dry forest) habitat is intact. Even within the name of the state were the clues as to what once was: ‘Mato Grosso’ meaning ‘thick woods.’ I asked my friend Dr. Fernando Carvalho, an ichthyologist and natural scientist with an intimate knowledge of the region’s history and biology, how long ago this landscape was transformed. 
 “A hundred years?” I asked. “Oh no, probably in the last 30-40 years” he replied. 

Something hit me in that moment. The quaint and pleasant landscape of the English countryside is, in fact, almost no different from the oceans of soy I was seeing here. The difference was time. Agriculture in the UK has seen the destruction of natural habitats and their conversion into crops and grazing land take place over thousands of years. The ‘real’ landscapes are long gone and what we see and imagine to be a natural idyl is a totally transformed and human landscape. When we look at the bare, dramatic, and to us iconic slopes of the Scottish Highlands, we are not seeing the forests that once covered them, now kept down and unable to return due to sheep grazing and grouse-shooting estate management. 

Unlike Brazil however, there are some causes for hope; there is more forest in the UK now than there was in medieval times, although the monoculture strategy of the Forestry Commission leaves much to be desired.

All this made me realise again, how the perceived hypocrisy of Europeans asking developing countries not to destroy and convert their natural landscapes must seem so frustrating. In Europe scientists and conservationists know what has been lost and are desperate to prevent it happening elsewhere. After all, if you burn your hand on the pan, you warn the next person it’s hot, right?

Plant life is abundant

Loricariid mecca

It’s hard not to be overwhelmed by the grim reality of the human war on nature, however, it is important to remember that many people are determined to save it and do their part, whether through choices in diet or consumption or though the work of the scientists who were in the car with me. 

We were constantly opening the windows to cool down before quickly shutting them again as red dust from the road filled our eyes. Finally, we arrived at a bridge crossing a wide, racing river within the property of a ranch. For Luiz and Heriberto Gimenes Junior, the loricariid enthusiasts on the team, this was mecca. I entered the water with my camera, hoping to film some of the armoured catfish that Luiz told us were here, but I soon realised that not being swept away, let alone doing any photography, was the real issue! 

The current was incredibly strong and with one hand holding the camera, I struggled to manoeuvre over boulders and gravel beds. Sometimes I was able to hook a finger into the many fissures and holes in the larger boulders and sheets of slippery rock and invariably I would startle some small Hypancistrus or Hypostomus species of catfish that had been sheltering there. Heriberto meanwhile was catching them with his bare hands, holding up specimens for me to frantically wave my approval at before the current risked lifting me from the riverbed.

I was hurled against great buttresses of stone again and again. The river was full of construction rubble, perhaps from 

the ranch and the bridge, and the broken bricks tore through my skin with wicked delight. Bruised and battered, I moved to the margins where I found Loricariids resting on branches or scuffling over sand. A few Astyanax tetras raced past and Luiz and his team caught several of them along with killifish, Melanorivulus dapazi, Rhamdia aff. quelen catfish, along with a very cute little Tatia catfish in their nets along the margins. Another nice find was a slender native livebearer, Cnesterodon sp. 

Headed down the steep banks

Later I asked the team to help me ID all the various species collected, but the consensus was that until the specimens were studied in a lab and formally described, most things were ‘sp.’ or in other words, an undescribed or new species. Heriberto suggested that all the loricariids we saw were likely undescribed. Luiz had taken us to a place where the fish fauna was quite literally unknown to science. I noticed small clumps of Eleocharis and Helanthium growing among reeds near the bank and even something that looked like Bacopa myriophylloides, clinging onto rock in the middle of the river, bent almost flat from the torrential flow. 

Frustrated at not being able to photograph, I hauled myself out of the water and was instantly set upon by very tiny, very numerous black flies which bit with a ferocity that would make a horsefly blush. I fled to our parked pickup. Luiz, grinning with his fishy prizes, asked me how I was. I explained the difficulty in not being swept away to which he cheerfully replied, “Good thing you weren’t, there’s a massive waterfall about 200m downstream”. Thanks Luiz. 

Hypostomus lurking under rocks

We gathered our gear and trekked through the dry scrub and grasses. Grasshoppers pinged up into our faces and the sun, which had been skulking behind dark, threatening clouds, erupted forth to bake us. Arriving at the waterfall, we had to shout to hear each other, even when stood side by side. The roar was incredible. We followed Luiz in single file down a slippery track, winding into another world, away from the hot sun and the dry scrub above. 

Rhamdia aff. quelen.

Crashing waters

The spray from the waterfall had created a green oasis flanking the falls. Ferns, vines and mosses covered the rocky slopes. Tall green shrubs shaded us as we grabbed onto lianas to stop from sliding down the muddy path. As we neared the base of the waterfall, I realised that the dominant plant, scrambling over everything and everywhere, was a species of Hydrocotyle. Luiz led us to a giant grotto, the space behind the waterfall. It was like every exotic adventure film you’ve ever seen. I gazed at where the water crashed into the river. It smashed down onto rocks and churned up the sand. If you had attempted to stand under the falls you would have been badly injured or worse. I thought to myself, ‘there’s no fish here.’ 

How wrong I was! 

Using the torch mounted on my underwater camera and floating in only a foot of water just behind the falls, I searched among the rocks. Heriberto, torch in hand was examining each crack and crevice and I soon realised the place was thick with small loricariids. This turbid, churning, but oxygen and rock-rich habitat was perfect for them. They were tricky to photograph however, as the moment I was close enough to take the shot, they darted into a hole or beneath an overhang of rock. I decided to simply lay on the sandy bottom and wait to see what appeared among the boulders. 

I felt something gently nibble my wrist and looking down, I saw that a gang of Pimelodella catfish (possibly P. gracilis or P. mucosa) were gliding about the sand and picking at me to see what was edible. I found that each time I moved and disturbed the substrate, they seemed overjoyed, flying in to hunt for any morsel I might have uncovered. I was more used to observing these graceful, lithe and charismatic fish in the Pantanal wetlands, where I’ve spent many hours following groups of Pimelodella mucosa over sandbanks or watching them at night from the bank with a torch as they shuffled and foraged near the margins. Several times I observed them feeding alongside the Pike cichlid Crenicichla semifasciatus, which bounces and hops along the substrate. The catfish and the cichlids moved together in a group. Perhaps the foraging and digging activity of the Pimelodella, finding food in the substrate with their sensitive whiskers and the chameleon like eyes of the Crenicichla, quick to spot any incoming danger, made for a good working team. 

Inspecting the waterfall catch.

Small bands of Characidium zoomed back and forth in the pulsating flow from the waterfall. They would sit on the substrate or perch on rocks and then suddenly lift off, swimming with jagged movements for several feet before descending like a flock of birds on the next rest spot. They were nervous and didn’t appreciate being followed, but I found that if I stayed still, then eventually they would come and investigate. 

Characidium, the ‘darter characins’, are some of my favourite fish. They are no colour and all character. Propped up on their strong pectoral fins, they sit on the substrate as their eyes rove about, searching for food and danger. 

My absolute favourite species is very small and not one I’ve seen in the hobby. Characidium laterale is one of the few species that spends most of its time swimming in midwater, alongside other characins and I’ve encountered and collected it more times than I can count in the Pantanal. In the Bodoquena highlands I’ve spent many hours watching the antics of C. aff. ‘zebra’ but I couldn’t confirm the identity of the species at the waterfall. Once again, when I asked the team to confirm my suspicions as to the identity of the Pimelodella and the Characidium, they merely replied “Pimelodella sp. and Characidium sp., for now…” The largest fish I spotted was a Leporinus, possibly L. frederici, as it zoomed past me and off into the gloom. 

The river above the waterfall.

While Heriberto and I splashed about, Luiz, Fernando, our friend Ricardo and other members of the team stood in great clouds of spray, casting nets and examining them. Several times they tripped over me as I moved in the shallow water, a case of too many scientists, rather than cooks. We spent several happy hours here and it truly felt like a mystical and special place — I could see why Luiz had been so keen to show it to us! 

The experience had reinforced the fact that almost anywhere there is water, there are fish. The three groups we had encountered, the Loricariidae, the Pimelodella and the Characidium were superbly well adapted to exploit this habitat. This was an excellent place to be! All they had to do was hang about and wait for the river to bring them edible items over the waterfall.
In the flow and oxygen rich water, algae and aufwuchs covered the rocks, sustaining the armoured catfish. The boulders provided plenty of cover and the water was too shallow for most predatory fish. We didn’t see any birds, but the roar of the waterfall and the overhanging cliffs might put off avian fishers such as egrets; there was too much cover which could obscure predators, no easy way out and the noise might drown out the approach of danger. Upstream, the habitat was also suited to loricariids, with fast flow, lots of rockwork and hiding places and again, not an easy place to be a predator. 

Torches help to find catfish.

I mean, of course there were fish here! Apart from insects, fish are the most speciose (with the number of species) group of animals on the planet. This may be due to their ability to adapt and thrive in such a vast array of habitats. It is not so much the case that every habitat can sustain at least one species of fish, but rather that there is almost always at least one species of fish adapted to live in a habitat. Think of the blind cave tetras of Mexico, the desert gobies of Australia, the tiny fish which live beneath the Antarctic ice, their blood containing a natural anti-freeze which allows them to survive and graze algae growing on the underside of the ice. 

The only places where fish truly struggle to survive are those too degraded and altered by human activity. The rate of change, destruction and pollution means that few, if any species can adapt in time to these threats. Later that evening, as we drove through the soy sea in the dying light, I wondered at the human ability to adapt in order to survive. Perhaps once we did so. Now we seemed to be adapting our world to suit us, to provide us with everything we could want and so much more. That felt like a very foolish strategy. Maybe one day when the world was nothing but monocultures and our rivers and seas were empty of life, we might think that it would have been better to adapt our needs and lifestyles, our mindsets, ethics, philosophies, industries and politics to allow us to live within the existing natural world, rather than alter it to our short-term benefit, which still left many millions if not billions living drastically unequal lives. Ah well, let them eat soy.