E. Cobham Brewer 18101897. Dictionary of Phrase and Fable. 1898.
Abstain from the Melanurus. This is the sixth symbol in the Protreptics. Melan-uros means the black-tailed. Pythagoras told his disciples to abstain from that which has a black tail, in other words, from such pleasures and pursuits as end in sorrow, or bring grief. The Melanuros is a fish of the perch family, sacred to the terrestrial gods.