Study of fish movements under constant conditions of light and darkness

This paper deals with the locomotor movements of four fish species, Salmo gairdnerii irideus Gibbons, Ambloplites rupestris rupestris (Rafinesque), Ictalurus nebulosus nebulosus (Le Sueur), and Lepomis gibbosus (Linnaeus), and the locomotor patterns displayed by non-conditioned animals in constant conditions of light and darkness.The entries into the 16 sectors of the tank were uniformly distributed; there was no preference shown by the fish for any one sector of the experimental tank, regardless of the light condition.Most animals with the exception of the rock bass displayed a definite pattern of locomotor movements, consisting of a range of turning angles. Variations in this pattern were not significant from day to day under similar experimental conditions of light.Frequencies of right- and left-handed turns showed individual differences in a large number of bullhead and pumpkinseed, whereas there were no differences in rock bass. Thigmotaxis and vision might play a role in this turning behavior.Animals displayed a different angular pattern of locomotion under light and dark conditions. Rock bass and pumpkinseed showed a preference for short angle turns whereas rainbow trout made turns of longer angles. Bullhead showed no change in the magnitude of the angles of turn.