IT'S WELL-DOCUMENTED THAT fish choose to navigate through their chosen environment in a multitude of different ways. Piscine perambulators seek the respite of the substrate, with weedy scorpionfish (Rhinopias frondose) utilising their pelvic and pectoral fins to stroll about, handfish using their pectoral fins like, well, hands, while brackish-dwelling mudskippers traverse the silty sediment by 'crutching', a movement akin to skipping. Up in the water column, the aptly named, ambush-hunting crazy fish (Butis butis) will hover in a variety of upturned positions, waiting to strike, while the upside-down catfish (Synodontis nigriventris) spends 90% of its time inverted.
Many free-swimming fish employ a standard propulsion technique - a horizontal stance in a forward direction. Termed Body-Caudal Fin (BCF) swimming, their anatomical design allows them to flex their bodies and generate undulatory…