Several fish with swimbladders have been shown to detect the angular location of a source of low‐frequency pure tones, e.g., 75 Hz, if it is situated in the “horizontal” plane of the fish. Moreover cod possess truly three‐dimensional directional hearing. Two variables are pertinent: particle acceleration a(t) and acoustic pressure p(t) at the position of the fish. Directional information in a(t) might be obtained through differently oriented acceleration detectors such as the otolith organs. Electrophysiological evidence supports this. Time of arrival differences appear irrelevant. Bony fish with swimbladders (cod, ide) show a 180° reversal in directional response if a sinusoidal sound field with a(t), p(t) is replaced by a(t), −p(t). This suggests a phase analysis to overcome the 180° directional ambiguity when inferring propagation direction from a(t). Pressure is transformed by the swimbladder into accelerations along a line of action characteristic for the recording site in the labyrinths. Sharks, which lack swimbladders, show acoustic attraction from afar. It is unknown how they are able to localize the source if the detection is also based on a phase comparison system.