Fig. 10. Schematic drawing (not to scale) that illustrates the pitching-moment balance in a forward-sinking parrot cichlid adopting a tilted-down swimming posture. The caudal fin wave of the parrot cichlid propagates dorsally. The purple curved thick arrows represent the induced pitching moment. M_B is the head-down pitching moment induced by the buoyant force (F_B). M_PF is the head-down pitching moment induced by the down-stroke force (F_PFD) of the pectoral fin; M_CFP is the head-up pitching moment induced by the caudal fin-wave propagation force (F_CFP). The behavior of a CFP functionally facilitates the pitching stabilization.