Acanthuridae ("thorn tail") is the family of surgeonfishes, tangs, and unicornfishes. The family includes about 80 species in six genera, all of which are marine fish living in tropical seas, usually around coral reefs. Many of the species are brightly colored and popular for aquaria.
The distinctive characteristic of the family is the spines, one or more on either side of the tail, which are dangerously sharp. Both the dorsal and anal fins are large, extending for most of the length of the body. The small mouths have a single row of teeth used for grazing on algae.
Most species are relatively small and have a maximum length of 15-40 cm, but some members of the genus Acanthurus, some members of the genus Prionurus, and most members of the genus Naso can grow larger, with the whitemargin unicornfish (N. annulatus), the largest species in the family, reaching a length of up to a meter.
Source: en.wikipedia.org/wiki/Acanthuridae - 26.03.2010
Life in the Water
Seeing such a fascinating beauty and strangeness we can nearly forget, that such a fish is a fellow creature with emotions, fears and wishes, too.