Back in April 1995, three friends and I flew to Columbia to search for new fishes, our main interest being cichlids. The last days of our trip were spent in the Caquetá-drainage, in a province named ‘paradise’ by its inhabitants. Here, we fished east and west of Florencia.
Some of our fishing locations we’d already read about, starting in the Quebrada Aguas Calientes — ‘the hot waters’ — a small river 28km west of Florencia; in some brooks between Belén and Morelia; and in the Río Montainita, some 5km from a town with same name. We also went east and fished around Esmeraldas.
At each site, the water flowed quickly but never warmer than 27°C. The pH ranged from 6.5 to 7, with the hardness barely registering at just 1°dGH/KH. The bottom of the rivers consisted of boulders, pebbles and sand, with some muddy areas full of dead leaves and some fallen trees here and there. The water was turbid (and colder) following rainfalls, clearing up in a few hours, and it seemed that the fish were quite used to these sudden changes.
The fish
The fish-fauna of the Caquetá-province in Columbia seemed similar to that of the upper Aguarico- and Napo-drainages in eastern Ecuador, where I had already fished a decade earlier.
We met many familiar faces. There were abundant knife-fish such as Eigenmannia virescens and Gymnotus carapo; giant freshwater-eels, Synbranchus marmoratus; catfish of Pimelodus and Pimelodella; armoured catfish including Hypostomus, Ancistrus, Chaetostoma, Loricariichthys, Rineloricaria, and Pseudohemiodon; Corydoras; characins from Moenkhausia, Hemiodopsis, and Leporinus; and, of course, cichlids like Aequidens tetramerus, Bujurquina cf. peregrinabunda and Laetacara flavilabris.
We had come to collect Caquetaia myersi and Crenicichla anthurus which we knew were in this area and were lucky to catch both on the first day. But there were also some surprises — a very big and colourful (and at the time still undescribed) Apistogramma, as well as an undescribed Heroini cichlid, and an undescribed Geophagus of the so-called surinamensis-group.
The non-cichlid catch
In the fast-flowing water, we detected some 5cm bottom-dwelling Characidium. They are able to remain stationary in the current, moving forward in a jerky way, using wood, stones and leaves as resting places.
In the free water, nicely coloured Astyanax bimaculatus of about 10cm were bustling about in groups, feeding on small invertebrates, detritus and the fresh tips of plants. As they are distributed from Panama southward to Argentina and have adapted to many different water parameters and temperatures, they are quite undemanding. In the wild, they start spawning at the beginning of the rainy season, so that their fry can find food easily. To spawn, males develop small hooks on their ventral and anal fins to ensure sufficient contact time with the females as they fertilise the eggs.
Nearly everywhere we found archaic ‘Trahiras’,
as they are called by the natives, specialised lurking predators with sharp and pointed teeth — Hoplias malabaricus. They may grow to 65cm or
so and are found close to the bottom, often lurking as ambush predators.
We also caught silvery Pimelodus blochii, a 35cm pimelodid catfish. It can survive in stagnant water where the oxygen is not sufficient because it’s able to take air from the water’s surface into its intestine which is rich with oxygen-extracting capillaries. It’s a greedy eater, swallowing any kind of food, even feeding on detritus when nothing else is to be found, and wanders upstream for reproduction. Fully grown females are believed to lay 50,000 eggs at one spawn!
Another pimelodid we caught (and found in the market) was Hemisorubim platyrhynchos, its species name referring to its flat ‘beak’. This shovelnose cat grows to 60cm total length and is distributed from the Orinoco down to the Parana. As it feeds mainly on fishes, its head is flat with a broad mouth, the upper jaw being shorter than the lower. Both jaws and its palate are toothed, and its eyes are placed so high that it can look about without lifting its head.