The visual challenges of short-range navigation in teleost fish.

To understand how fish use vision to navigate, we must first understand what they see. This Review explores how visually guided navigation in teleost fishes is shaped by the structure of their visual systems, the cognitive processes that interpret sensory input and the dynamic environments they inhabit. With broad variation in habitat, ecology and visual capabilities, fish provide a powerful system for examining how sensory conditions influence navigation. We focus on short-range navigation and review core strategies - beaconing, pilotage, path integration and spatial mapping - alongside the visual and cognitive demands each entails. To assess which strategies are available to different species, we examine the visual processing pathway, from eye and retinal anatomy to behavioural evidence from cognition studies. These reveal that fish process visual information in a variety of ways to perform a diverse range of visual functions, including motion perception, object recognition and generalisation across viewpoint or lighting changes. We consider how sensory limitations and visual noise may constrain navigational accuracy, and how context or visual ability might shape which strategies are used. Environmental changes, such as turbidity, light pollution, or habitat degradation or shifts, can further degrade cue availability and reliability, affecting navigational performance. Understanding how visual information is received, processed and applied is therefore essential not only for interpreting observed behaviours, but also for predicting how fish may respond to changing environments. By linking sensory input with spatial behaviour, we propose a framework that integrates perception, cognition and movement, offering new insight into how diverse visual systems shape navigation across species.