Example of a fish orbit (here, a (y, z) fish), i.e. 3 : 2 resonance between two orbital frequencies (here, Ω_z and Ω_y, also called (0 : 3 : −2)). Upper panel: Orbit plotted in the (x, y), (x, z) and (y, z) planes. Lower panel:R_max vs. z_max diagram (left) and Cartesian frequency map (right). The coloured markers correspond to the fish and anti-fish orbits identified with the visual method (see 4.2.2).