Tool-Like Behavior in the Sixbar Wrasse, Thalassoma hardwicke (Bennett, 1830)

There are only a few documented cases of the use of either tools or substrates (anvils) as pseudotools in fishes. Described here is an anvil behavior of a labrid fish, Thalassoma hardwicke, observed under aquarium conditions. This fish was fed with pellets that are too large to swallow and too hard to break up into manageable bits using jaws only. The observed individual carried a pellet to an anvil to break it up into pieces small enough to be swallowed. This feeding behavior was frequently repeated (observed in detail about 15 times), nearly always successful, and remarkably consistent, suggesting that the rock selected for an anvil is remembered and its functional qualities or other factors may play a part in its choice. These observations agree with evidence for other advanced cognitive abilities in members of the genus Thalassoma and suggest that, for welfare demand, rocks with rough surfaces should be provided to these fish, especially when they receive hard food for variety. Zoo Biol 29: 767-773, 2010. (C) 2010 Wiley-Liss, Inc.