Head anatomy of Aplocheilus lineatus. (A)The killifish hunts with its head immediately below and parallel with the surface of the water, maximizing its sensitivity to capillary waves. Scale bar, 10mm. (B)The array of specialized neuromasts occurs on the fish's flattened head between the eyes and behind the prominent semicircular lip. (C)In a fluorescence micrograph, labeling with a red fluorophore concentrated by hair cells reveals the positions of the largest 16 of the 18 neuromasts. Scale bar, 5mm. (D)Superposition of the previous two images reveals the position of the neuromasts on the dorsal surface of the head.

From: A hydrodynamic sensory antenna used by killifish for nocturnal hunting
Jason S. Schwarz, Tobias Reichenbach and A. J. Hudspeth
Journal of Experimental Biology 214(Pt 11):1857-66 June 2011 
DOI: 10.1242/jeb.051714