Hunting Strategies of a Lake Malawi Cichlid with Reverse Countershading

Abstract

Tyrannochromis macrostoma (Regan), a haplochromine cichlid fish endemic to Lake Malawi, Africa, exhibits reverse countershading. It attacks potential prey fishes from an upright, sideways (90* rotation from an upright position), or upside-down (180* rotation from an upright position) positions. Seventy percent of its attacks are from a sideways position. Whenever it was observed attacking from an upside-down position, its prey was stationed below the attacker. When attacking from a sideways position, its prey was below the attacker 25% of the time and on the same plane 75% of the time. When attacking from a normal position, its prey was below the T. macrostoma 82% of the time and on the same plane 18% of the time. Data presented herein lend credence to the self-shadow concealment explanation for the selection of countershading. Tyrannochromis nigriventer Eccles, a closely related species, does not display reverse countershading but occasionally attacks from an upside-down position.