Constantly one encounters the designation “L 56” in stock lists, in shops as well as in many many lists of aquarists. This refers to Parancistrus aurantiacusthe “Golden Broad-headed Sucker Catfish”, but this species does not have an L-number and should never have been given one, because it was scientifically described by CASTELNAU in 1855 and therefore does not fall under the fish numbers were given to: a species that is indeterminable at the time of number assignment and therefore “deserves” an L-number.L 56 is an undescribed Guyanancistrus from the Rio Araguari in Amapá, Brazil. The species was introduced in DATZ (02/1990) in 1990 and is not known to aquarists. Five years later L 56 was erroneously associated with Parancistrus aurantiacus in Aqualog (Glaser & Glaser, 1995) and since then this false name has persisted.
Now one can cling to the Thomson-theorem and suggest that everybody knows what is meant by the name and which species is offered, or one simply tries to use the correct terminology and calls a described species by its scientific name and not by a – even wrong – “placeholder”.
In the BSSW-Report 03-04/2018 there is a very comprehensive article about the genus Parancistrus, including practical propagation experiences for everyone who is interested in these great catfish!