The maximum swimming speed of a fish is somewhat determined by the shape of its body and tail and by its internal temperature. The cosmopolitan sailfish (*Istiophorus platypterus*) is considered to be the fastest fish species, at least for short distances, swimming at greater than 60 miles per hour (95 kilometers per hour). Some American fishermen, however, believe that the bluefin tuna (*Thunnus thynnus*) is the fastest, but the fastest speed recorded for this species so far is 43.4 miles per hour (69.8 kilometers per hour). Data is extremely difficult to secure because of the practical difficulties in measuring the speeds. The yellowfin tuna (*Thunnus albacares*) and the wahoe (*Acanthocybium solandri*) are also fast, timed at 46.35 miles per hour (74.5 kilometers per hour) and 47.88 miles per hour (77 kilometers per hour) respectively during 10- to 20-second sprints. Flying fish swim at 40-plus miles per hour (64-plus kilometers per hour), dolphins at 37 miles per hour (60 kilometers per hour), trout at 15 miles per hour (24 kilometers per hour)—and humans can swim 5.19 miles per hour (8.3 kilometers per hour).