L-number
A semi-scientific classification for loricariid catfish before formal description.
The L-number system is a semi-scientific classification system for catfish of the family Loricariidae, based on photographs of shipments published by the German aquarium magazine DATZ (Die Aquarien- und Terrarienzeitschrift). It provides a common-name identifier for loricariid catfish before they receive an official scientific name, with the first L-number published in 1988.
- First published
- 1988
- Publication
- DATZ (Die Aquarien- und Terrarienzeitschrift)
- Family
- Loricariidae
- Prefix
- L
- Alternative prefix
- LDA (from Das Aquarium magazine)
Lore & Background
The L-number system originated from the German aquarium magazine DATZ, which began publishing numbers based on photographs of shipments of tropical catfish in the family Loricariidae. The first L-number appeared in 1988. This system is not a formal scientific designation but allows hobbyists to identify catfish by a common name before the fish is officially described by science. When a loricariid receives an official scientific name, the L-number is retired, and best practice is to then use the scientific name. A specific L-number does not guarantee a discrete species; multiple L-numbers have been given to different populations of the same species, and conversely, a single L-number may be used for multiple species. The aquarium magazine 'Das Aquarium' introduced a similar system using the prefix 'LDA'.
Reader's Guide
The L-number system is significant as a practical tool for fishkeepers to identify loricariid catfish prior to formal scientific description. It fills a gap in taxonomy by providing a consistent reference based on published photographs, allowing enthusiasts to discuss and trade fish with a shared identifier. However, the system has inherent limitations: an L-number does not guarantee a single species, as multiple numbers may refer to different populations of the same species, and one number may cover multiple species. This ambiguity means that L-numbers should be treated as provisional labels rather than definitive taxonomic units. The retirement of an L-number upon official scientific naming underscores its temporary nature, and best practice is to adopt the scientific name once available. The parallel LDA system from 'Das Aquarium' adds another layer of identification, though both systems serve similar purposes. The numerical order of L-numbers gives precedence to the lower number over higher or alternative numbers, but these may still describe the same species or type from another locality. Overall, the L-number system remains a widely used reference in the aquarium hobby, despite its acknowledged imperfections.
Frequently Asked Questions
What is an L-number in the aquarium hobby?
An L-number is a semi-scientific identifier assigned to species of loricariid catfish (family Loricariidae) that have not yet received a formal scientific name. It gives hobbyists a practical common-name reference so they can discuss and trade these fish before a taxonomist completes a full description.
Where did the L-number system originate?
The system was built around shipment photographs published in the German aquarium magazine DATZ (Die Aquarien- und Terrarienzeitschrift), which catalogued newly arrived loricariid specimens. The very first L-number appeared in that publication in 1988.
What is the difference between an L-number and an LDA number?
Both serve the same purpose of identifying undescribed loricariid catfish, but they come from different German magazines. The L prefix is tied to DATZ, while the LDA prefix originates from the magazine Das Aquarium.
Why do aquarists still use L-numbers if the fish eventually get a real name?
Many loricariid species circulate in the trade long before a valid scientific description is published, so the L-number fills that gap as a widely recognized shorthand. Even after a binomial name is assigned, the original L-number often persists in hobbyist forums, shop listings, and community guides.
Are L-numbers a fully scientific classification?
No; they are explicitly semi-scientific, functioning more as a cataloguing shortcut than a taxonomic authority. They do not encode phylogenetic relationships or meet the standards of the International Code of Zoological Nomenclature, which is why a formal species description can still override or reassign them.
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