Performance and maneuverability of three species of teleostean fishes

Abstract

Whole-animal behavior and performance are assembled from functional capabilities that are dependent on morphology, such as body form and fin-distribution patterns. We compared hovering, median and paired fin (MPF), body and caudal fin (BCF), and burst-and-coast gaits and maneuvers permitted within these gaits, turning, backward swimming, and braking for three species: goldfish, Carassius auratus, silver dollar, Metynnis hypsauchen, and angelfish, Pterophyllum scalare. Goldfish have a fusiform body with a relatively small surface area and depth. Silver dollars and angelfish had larger areas and depths. The smaller surface area was expected to be associated with greater use and higher speeds in BCF swimming behaviors for goldfish but little support was found. Larger body depth was expected to be associated with higher turning rates and maneuverability of silver dollars versus goldfish, but data were again equivocal. Body depth may be more important in defense than in locomotion. Goldfish and silver dollars have ventral paired fins. Angelfish have more derived lateral pectoral fins, anterior pelvic fins, and larger median fins. This fin pattern was expected to be associated with greater use of MPF behaviors at higher speeds, and with greater maneuverability. Support for this expectation was found, but there were sufficient exceptions to indicate that other factors were important.