All that glitters is not gold: different anti-predatory behavior of two color morphs of goldfish (Carassius auratus)

Abstract

The foraging behavioral responses of individuals from two color morphs of the common goldfish (Carassius auratus) to a foraging predator, the little egret (Egretta garzetta) were tested in two artificial theaters, each containing three fish ponds. Each pond contained two distinct microhabitats for the fish: 1. A safe microhabitat: a sheltered area under an opaque cover at the center of the pool providing a refuge but no food. 2. A risky microhabitat: the rest of the pool area, where the fish could feed but were exposed to predation by egrets. This experimental design forced the goldfish to trade off food and safety, and to manage risk via time allocation to each microhabitat. The foraging behavioral responses of the gold variant and the bronze variant goldfish, one morph at a time, were quantified. In the presence of an egret, bronze morph fish spent significantly more time out of cover and more fish emerged from under the cover at any given time than did the gold morph fish. Despite the greater exposure of bronze morph fish, they were captured significantly less often by the egrets. These findings strongly suggest that differently colored fish may perceive predation risk differently, trade off food and safety differently, and may have different susceptibility to predators. Our results show that color variation in goldfish may affect both foraging behavior and anti-predatory behavior.