It looks like my parents will be coming to Champaign this Sunday.
The glowlight tetra (Hemigrammus erythrozonus) is a small brightly colored schooling tetra from the Essequibo River in South America. They are reasonably popular as aquarium fish as they are brightly colored, hardy, unaggressive and breed readily in captivity. Interestingly they also have an alarm chemical in their body, so that when they are eaten by predatory fish the fish excudes pheromones that alert other glowlight tetras. This was tested using small shoals of glow light tetras and exposing them to Jack Dempsey cichlids with different diets. The tetras had a very different response to Jack dempseys that had not eaten glowlight tetras. Glowlight tetras that sensed these pheromones began flicking their fins to alert the shoal of the predator. In some cases it was found that the predators were also deterred by the fin flicking behavior.