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The Fishy Mystery of Lake Malawi


Stacks of rocks, like these in Lake Malawi National Park, are a favorite dwelling place for mouth-brooding cichlids. They dart behind the stones for cover when frightened. (Getty Images)

BY BEN CRAIR

In the second-largest lake in Africa, fish evolution is taking place at an explosive rate. Why? Scientists are diving into the question

first learned about cichlids when I was a boy, shopping to fill an aquarium. I’d wanted a saltwater tank, because its inhabitants tend to be so much more colorful, but my parents nixed that idea as too demanding. I was getting ready to resign myself to boring guppies, plastic plants and a catfish sucking algae on the glass when the man at the aquarium shop showed me the cichlids. They came from a freshwater lake, he said, but they were as colorful as the residents of any coral reef. I paid a few dollars for a pair of electric yellow Labidochromis caeruleus, and so began my fascination with an animal that would have amazed Darwin if only he’d known about it.

 

Cichlids are found all over the world, mainly in Africa and Latin America, but they’re especially abundant in Lake Malawi, where they’ve diverged into at least 850 species. That’s more species of fish than can be found in all of the freshwater bodies of Europe combined.

Though my interest in fishkeeping lasted only a few years, the allure of Lake Malawi never faded for me, and last September I finally made the journey to what is arguably the planet’s most vibrant body of freshwater. Malawi is a tiny landlocked country wedged between Zambia, Tanzania and Mozambique. The Great Rift Valley runs through the country lengthwise and Lake Malawi lies to one side of it, covering most of the country’s eastern border. I was going to meet Jay Stauffer Jr., a Penn State ichthyologist and one of the most respected cichlid experts in the world. Stauffer himself has discovered more than 60 new cichlid species in Lake Malawi, and his work is far from finished.

“About half the species in the lake still haven’t been described,” Stauffer told me when he and his driver, Jacobi, picked me up at my hotel in the capital city of Lilongwe. Stauffer wore a Penn State T-shirt tucked into cargo pants and spoke with a slow drawl. He has been visiting Malawi on and off for more than 30 years, and as we rode in a Land Rover to the lakeshore he told me about his four bouts of malaria and the local putzi flies, whose maggots burrow beneath human skin. This was the arid season, though, which meant fewer mosquitoes and other airborne terrors. Dry riverbeds scarred the landscape, and parched clay and wilted grass scabbed over the fields. The roads out of Lilongwe were lined with stalls, where women sold potatoes from meager rafts of shade.