Type of lake formed by accummulation of water in a volvanic crater or caldera.

Lake Pinatubo in the Philippines is a typical crater lake. © Chris Tomnong

Name often given to the Amazon River main channel from its confluence with the Rio Negro upstream to the border of Brazil and Peru. Often used interchangeably with ‘Amazon’ to describe this stretch.

Coding system used to organise and refer to unidentified catfishes, though not necessarily undescribed or distinct species, of the genus Corydoras. Works in tandem with the similar C number system.

The system was invented by Ian A. M. Fuller in reference to his website ‘Corydoras World’ but is now in popular use worldwide.

Coding system used to organise and refer to unidentified catfishes, though not necessarily undescribed or distinct species, of the genus Corydoras. Works in tandem with the similar CW number system.

The system was invented by German aquarist Hans-Georg Evers and first appeared in the magazine ‘DATZ’ but is now in popular use worldwide.

A stream that has no permanent tributaries, often very short.

Mountain range extending southwards down the western side of India from the borders of Gujarat and Maharashtra states, through Maharashtra, Goa, Karnataka, Tamil Nadu and Kerala as far as Kanyakumari district in Tamil Nadu.

The Ghats are a UNESCO World Heritage Site and represent one of the eight hottest hotspots of biological diversity in the world, and is home to a number of endemic fish species.

Latin term meaning ‘of authors’, often used to indicate that a name is being used in the (different) sense of a number of subsequent authors and not as established by the original author. Abbreviated to auct. or auctt.

See nominal taxon.

A nomenclatural concept denoted by an available name used in an original description, and based, actually or potentially, upon its name-bearing type but having no defined taxonomic boundaries.

Often used when the precise definition of a species or genus is unclear, such as when a name may refer to more than one taxon and is therefore in need of clarification.

Migrating from fresh to salt water or from salt to fresh water at some stage of the life cycle other than the breeding period.