Behavior of the Fish Medaka under Microgravity

Abstract

As one of the space biology experiments for the second International Micro-gravity Laboratory ( IML- 2 ) mission scheduled in the summer of 1994, the project of 'Mating behavior of the fish, medaka '(Project name “MEDAKA”)has been selected. For the preliminary experiment, parabolic flights were carried out to observe the fish behavior under μG for five different inbred strains of medaka. There existed a clear strain-difference in the behavioral response of the fish under μG and light conditions: Some strains looped and other strains did not. However, under μG and dark conditions, all the fish of the five strains did loop. This indicates that fish use visual senses in controlling their posture under μG. In the laboratory, visual acuity is checked for each strain and also for F1generation between two strains, using a rotating striped-drum apparatus.