Despite the commonly held view that flatfish can change their surface markings to match their background pattern, there have been few systematic studies and it has recently been claimed that their capacity for such adaptive changes is minimal. Here we show that the tropical flatfish Bothus ocellatus can achieve pattern-matching with surprising fidelity. By adjusting the contrast of different sets of 'splotches' of different grain size (or spatial frequency) on the skin, the fish can blend into a wide range of background textures in just 2-8 seconds.