Spatial memory, landmark use and orientation in fish

Abstract Fish are a large and very successful taxonomic group. There are over 22 000 living species of tleosts (Pitcher 1993) and the cartilaginous fish, such as sharks and rays, swell the numbers even more. Being such a large group, fish are found in a wide range of aquatic habitats. For example, some fish live in, and swim around, highly, colourful and visually rich coral reefs while others explore and live in underwater caves, or at extreme depths where little, or no, light penetrates. This diverse array of habitats has led to fish facing many different types of spatial problems. Spatial orientation and memory are fundamental for all fish, from those that remain on a very restricted area of a reef, or coast, to long-distance migrants. An ability to track current location relative to the position of important features in the environment, such as shelter, will increase a fish’s chances of escaping from predators. Generally, efficient movement is aided by a map and an animal that knows the location of different resources with respect to one another can construct a map for a familiar area.