A Comparison of Detour Behaviors in Some Marine and Freshwater Fish Species.

Evidence of detour ability to reach a salient goal in marine fishes (, , ) and freshwater fishes (, ) has been observed using a "four-compartment box task" with an opaque barrier. The first experiment investigated this ability in marine fishes (, , ). Fish were placed in a four-compartment box, with social stimuli not accessible due to an opaque barrier. Two symmetrical apertures midline in the corridor allowed the fish to temporarily abandon the goal's view and attempt to circumvent the barrier. Marine fish showed searching behavior in the two compartments near the social stimuli. In the second experiment, the detour abilities of a marine fish () and two freshwater fishes (, ) were compared using a modified version of the apparatus, with elongated compartments continuing further from the obstacle barrier and social stimuli. This enabled the evaluation of the dependence on effective distance to achieve the social goal. Both marine and freshwater fish exhibited detour skills. Additionally, 's differential spatial explorations inside compartments supported an active interest in searching for conspecifics, suggesting possible social object permanence retention. Overall, these results highlight the ecological salience of detour skills in fishes, irrespective of species-specific adaptations.