The L-number system is a semi-scientific classification system of catfish based on photographs of shipments of tropical catfish of the family Loricariidae published by the German aquarium magazine DATZ (Die Aquarien- und Terrarienzeitschrift (The Aquarium and Terrarium Magazine)).
The L-number system is an approximate scientific categorization method for catfish based on photographs of shipments of tropical catfish from the Loricariidae family published in the German aquarium magazine DATZ (Die Aquarien- und Terrarienzeitschrift).