Rock Art May Change How We Keep our Fish (but probably not a lot)

Posted by Ruth McDonald on


The announcement of thousands of cave paintings in the Serrania la Lindosa in Columbia may seem like a mildly interesting bit of news, but only really for archaeologists and historians right?

 Think again. There is a fascinating wealth of information from these records that can help us fish keepers thousands of miles away, and raises an interesting question about when we should take our information from.

 What the hell am I talking about? Think about it, in a rapidly changing climate we know that many species are being driven to the brink (although there was some good news about fish that are hanging around coral reefs earlier this year), so if we want to provide our fish with the best conditions is it really the best thing to be taking them from now?

The changing Amazon

 Michael Goulding writing in his book Amazon the flooded forest (grab it here, it’s a nice readable look at the Amazon River and the surrounding forest) says …

“Of all the tropical theatres of evolution, South America claimed the most diverse cast of species. This is in large part because the Amazon basin provided ideal conditions for the radiation of life into an almost unbelievable number of niches.”

The Amazon River as we know it is a geological baby, only about 10 million years old. Compare this to the Thames that in various guises is about 140 million years old. Although only the last 7000 years of that has been as the river in it’s own right.

 The Amazons earlier years are hidden from us. The sandy soils mean that fossils aren’t preserved, and the records left in the ground are fragmented and difficult to interpret. What we do know is that abut 18000 years ago sea levels were lower as the ice age reached it’s peak, some studies sayingnearly 130m lower than they are today. These lower sea levels turned the gently flowing Amazon into a high speed slip and slide, flying down from the mountains and excavated deep channels and valleys.

 Things don’t say the same, and it seems about 6000 years ago the sea levels around the Amazon were much higher, again some studies saying about 130m higher than they are today. The sea dammed back that fresh water and drowned the forests, reaching across the valleys and flood plans to transform these landscapes.

 Between these two points we have the rock art. Dated to about 12 500 years ago (according to the newspaper article I read. The actual study hasn’t been published. Some people are saying it will be decades before they’ve done anything close to a comprehensive survey. But follow for more info) this literally paints a different picture to the Amazon we know today.


 But even before we look at the art. What do the fish tell us. Look at the cardinal and neon tetra. You have to agree there is some serious overlap between those two species. Cardinals comes from the quiet black water rivers. The water that looks like tea comes from the huge amounts of organic matter that the forest provides. Layers of leaf matter is washed into the rivers, and the poor soil conditions mean that it isn’t broken down into it’s chemical building blocks. Instead it stains the Rio Negro and the other rivers that so many of our fish call home.

 The neon on the other hand doesn’t come from these tea stained waters. That comes from much further west. From waters stained the colour of milky coffee by the silt washed from the Andes mountain into the water. But here’s an interesting thing. Want to see why I love Neons? Build them a blackwater set up. Then you’ll see. Little glowing beacons of colour in the tea stained waters. 15 million years since the Andes rose and changed what was likely a completely black water river into two distinct river types Neons are still reminding us of their origins in the tannin rich waters of the early Amazon.

So what do the paintings tell us?

That early man, or woman had way too much time on their hands, seriously what genius thought farming was a good idea. Hunter gatherers have far more time to do stuff, and this group of people recorded thousands of images on the cliffs. There are 8 miles of paintings, and it’s so high they’re having to use drones to survey it all. Which does bring the idea of a harpy eagle meeting a drone to mind. Go google it if you haven’t got the image of a harpy Eagle burned into your brain. Yes they are that big, yes they eat sloths.

 José Iriarte, a researcher from the University of Exeter who is working on the project says “there’s the diversity of the paintings,…From aquatic environments you have fish, turtles, anacondas, boas. But you also have birds, like eagles and king vulture. Then, of the terrestrial animals, monkeys, deer, giant sloth, and horses.”

 It will take generations to record and analyse the images, but there is one animal that is crucial there. The giant sloth. Along with the mastodon, palaeolama, and Ice Age horses these images point to a totally different landscape.

 We don’t know the exact species, yet, but the giant sloth inhabited grasslands and lightly wooded areas. It was adapted to temperate and semi arid habitats. The mastodon  is a crucial for dating these paintings. By 11 000 years ago they had become extinct, although we honestly don’t know why. The palaeolama is an extinct branch of camels, that were originally thought to be early lamas. Interestingly they were adapted to low-temperate, arid climates and preferred open, forested, and high altitude mountainous regions. Not exactly the wet warm and humid Amazon region we know.

 Finally the ice age horses again we are probably looking at grassland habitats, but lets not discount the idea of these animals being in an unusual ecological niche. Just to you know be contrary.

 This all tells us that about the time these people were recording the world around them on these towering cliffs, the world they lived in was different. Open temperate arid grasslands were close enough that they could see and hunt these species. The towering rainforests may not have been the feature that they are today, and the fish in the rivers may well have been living an entirely different life.

 But something was approaching. 2000 years later that megafauna was gone, and we don’t know why. We know that the climate changed. We know humans arrived and started hunting. We know that the seasons shifted. We know that there was a mass extinction. These broad strokes are all we know. The thin soil and the sandy levels below don’t preserve archaeological evidence too well, and other than this and other examples of rock art we have very little recorded by the humans.

 We also know what survived and thrived in the thousands of years before we humans showed up, until logging and farming, and mining changed the colour of the water itself. Before we set fires to destroy the trees that make this area so unique, and before we started polluting the waters and built dams.

 So what does these cave paintings tell us? They are clues to a rapidly changing world that has forced and allowed so many species into these fabulous niches, carving out space for fish to adapt, and thrive. They also show us that there are a lot of things that changing temperatures, vegetation, or water quality has driven to extinction.

 What should you do. Find out what area of nature your fish have evolved to thrive in, if you can go back a few hundred years, and look at that waterscape. There you will find the truth of your fishes evolution.

 Did you enjoy reading this? If so maybe you could support me on Patreon? As well as falling down rabbit holes of research I represent the UK fish Keeping Hobby as the Chair for the fish sub taxa committee on the Companion Animal Sector Council. Basically we advise government on fish, and fight to stop legislation that will damage our hobby. If that’s not enough then I also do a fair bit on social media to help others with their fish, and I am working hard with projects across the world to try and help fishy conservation.

 Want to know more on this topic? Let me know and it may well become a podcast episode 😊

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