The freshwater rays at the Mavicure Mountains
Anyone who has ever seen bottom-dwelling rays (not manta rays and eagle rays) in the sea tends to associate them with large sandy areas. With freshwater rays, there is of course also a great chance of seeing them in sandy areas, but the rays have also been encountered in habitats where we wouldn’t expect them!
We travelled south along the Rio Inirida from the Mavicure Mountains and stopped at a small tributary that contained clear blackwater. Walking along the river was a bit tedious as the bottom was muddy and there were countless dead branches in the narrow riverbed.
But a nice little blackwater river is often worth visiting and so we struggled upstream. After a hundred metres we left the mud and branch zone behind and were comfortably able to walk along the bank. And then we were surprised: a ray about 40 cm wide was swimming in water only a few centimetres deep in the stream, which was exactly 40 cm wide in some places!
It was exactly at that point that one of our group almost stepped on a juvenile and only his neoprene diving shoes prevented a severe injury from the ray sting. The indigenous guides who accompanied us took a close look at the "mini-wound", as they had all had unpleasant experiences with ray stings. Snorkelling in shallow water, we were able to observe the rays at our leisure. They were often lying ON the leaves that covered the river bottom. Not a single ray was burrowed in. They even patiently accepted our careful touching from the front at their fin seam. This mirrored our experiences with marine rays, which also never reacted aggressively. The famous fatal accident with the Crocodile Hunter, Steve Irvin, happened when he approached a resting ray from above. The ray felt threatened and whipped its tail from below into the unfortunate Steve's heart with its stinger, which was about 20 cm long. But rays almost always tolerate cautious approaches.
If you approach the rays cautiously, there is no danger at all
Freshwater rays also have a really bad reputation among the locals. Injuries caused by their stingers heal extremely badly and almost always become infected. I showed them how to approach the rays gently and how to touch them without them stinging. It’s approaching them from above and, of course, stepping on them that causes them to sting.
In addition to the rays, this stream was a nice biotope for cardinal tetras and freshwater hatchetfish. But the tetras did not form a shoal, but rather swam in mini groups of 3-6 animals through the shallow bank area of the stream. Directly above them were the freshwater hatchetfish, which were incredibly beautiful to look at! Depending how the light fell, their brown and white stripes were sometimes good camouflage and sometimes as striking as a chrome spotlight.
We had a a special encounter with the hoplias (Erythrinidae) which were also there. Normally you scare up the well-camouflaged predators on the ground when snorkelling and they disappear like a torpedo out of sight. Here, however, they remained calm and relaxed to be photographed! A great experience.
The camp was located at the foot of one of the cone-shaped Mavicure Mountains. They were formed by lava that pushed upwards from the earth's interior against the earth's crust without breaking through it. The result was bubbles in the jungle that were thrown up in a cone shape up to 700 m high. You could climb up one of the mountains. Exhausting, but worthwhile!
The view of the river and the jungle from the mountain was worth the arduous climb
You can climb up one of the Mavicure Mountains and get an incredibly beautiful view of the Rio Inirida, the other Mavicure Mountains and the surrounding jungle.
| Measurements |
Values |
| Water temperature |
27 °C |
| Conductance in µS/cm |
15 |
| GH |
|
| KH |
|
| pH |
5.0 |
