Nkwichi Blog

The Cichlids of Lake Malawi

Imagine a creature so savage that it targeted only the eyes if its prey, ripping them out with its teeth and chomping them down. Or another that only savours the taste of the young. They may sound like villains straight out of a cheap horror film but they are, in fact, two of the species of Cichlid fish from Lake Malawi/Niassa, and these are just some of the weird and wonderfulways that these endemic rainbow-coloured fish have developed over the years in order to catch their prey.

In fact, Lake Malawi offers one of the world’s best examples of the evolutionary process. Rising and falling water levels over millennia created the perfect conditions for the endemic fish to adapt to their changing environment until we’ve reached the level where there are so many different species in the lake, we still have no idea how many there are actually are. Experts reckon on between 600 and 1000 species. To put this in perspective,that’s more types of freshwater fish than Europe and North America combined. Not for nothing have the WWF named Lake Malawi the most important lake in the world in terms of biodiversity.

Take Trematocranus Placadon, which highlights perfectly the symbiosis between the Cichlids and their environment, and their ability to adapt. This fish survives on a diet of snails, but only develops the appropriate teeth when the snail population reaches a high enough level. With such a natural advantage, the snail population soon drops again, Trematocranus loses its teeth, and the ability to eat the snails, whose population then grows starting the process again.

Many of the species develop such specialized talents. Nimbochronis Livingstonii, commonly known as a ‘Sleeper’, has patchy black and white scales and when it lies on the bottom of the lake, belly up, it mimics something dead and rotten. Small, curious and hungry fish then descend to feed on this apparent tasty treat, which is when it leaps up and swallows them.

And in fact there a vast number of Paedophages, fish who go after the young of other fish, and so some mother fish, known as ‘mouth brooders’, keep their young in their mouth for safety. Yet again however, other fish have then developed specializations to deal with this; one species repeatedly rams the side of the mother fish until she spits out her babies.

Indeed it is this adversity that leads to such diversity, and the myriad examples of nature’s unique ability to adapt and survive. With the annihilation of Lake Victoria’s fragile eco-system, which used to hold hundreds of Cichlids and which now holds just 15, the importance of Lake Malawi cannot be understated, and its future will depend on our own ability to adapt, and to learn from such mistakes.