Found in the rivers and lakes of Central Africa within the Congo Basin, the upside-down Catfish is a curious creature. Aptly named for its habit of swimming and feeding whilst upside-down, it’s an extremely popular species in home aquariums and seems to have been admired for centuries as their images have been found in ancient Egyptian art.

In the wild, it often grazes on the undersides of submerged branches and logs so swimming upside-down makes these areas easier to reach, but it also tends to feed whilst upside-down at the surface too – often spending up to 90% of its time in the inverted position. As it generally feeds in areas with lots of vegetation at the surface, this means that it’s more important for it to be able to see what’s going on beneath it rather than above it, so it evolved to swim upside-down and keep a lookout for sneaky submerged predators.

What this also means is that its natural colour scheme is inverted in comparison to other fish, resulting in a belly that’s darker than its back, and its scientific name nigriventris literally means “black belly”. This acts a basic form of camouflage, making the fish harder to spot by predators above it such as birds, and it just goes to show that if you’re going to buck the trend and be different, it pays to have all the bases covered...