While we may not be privy to many of their conversations, many reef fishes are very vocal! The "loudest" sound producers are the toadfishes, squirrelfishes, drums and damselfishes. Some of these vocalizations are produced during courtship or spawning. They can consist of growls, clicks, grunts, chirps, hums or knocks. Sounds are often produced during aggressive encounters between members of the same or different species. Such is the case with many angelfishes, like the emperor angelfish (Pomacanthus imperator) heard on the clip below. The knocking sound you hear was produced when this particular fish would get annoyed - usually when another fish in the aquarium moved into its favorite cave. So next time you here an odd noise emanating from your aquarium, it may be that your fish are talking to you (or more likely to some of their tankmates)!
