Since a rolling moment grows slowly at the beginning of a roll, stabilization may be enhanced by unilateral thrust forces generated by powered fin movements early on. Quicker correction times for rolling perturbations may also reflect contributions from passive mechanisms. which possess a hydrostatic rolling equilibrium because the gas bladder and COM are positioned at the same height. In the absence of powered motions, simply the posture of the fins may also facilitate self-righting behaviour when water moves relative to a fish. The shape of the body and fins and their intrinsic
compliance can also contribute to passive mechanisms of stability. In response to sudden postural disturbances
caused by jets of water, fusiform-shaped fish can selfcorrect more quickly than laterally compressed fish