Some of the terms used in this atlas may be unfamiliar to amateur biologists, and so I provide this glossary. The definitions provided here relate only to the way the terms are applied to fish.
Adipose eyelid – thick, fleshy tissue that surrounds and partly covers the eye
Adipose fin – a small fleshy lobe on the back between the dorsal fin and caudal fin
Aestivate – to be inactive during warm or hot, dry periods
Anadromous – refers to fish that mature in the sea but migrate to fresh water to breed
Anal fin – the unpaired fin on the ventral or underside of the fish just behind the vent. The base of the anal fin is where it joins the body. To determine if the anal fin is short or long based, press the fin up flat against the body. If the base of the anal fin is shorter than the longest ray in the anal fin then the anal fin is short-based. If the base is longer than the longest ray, then the anal fin is long-based.
Barbel – whisker or finger-like appendages around the mouth
Benthic – living on the bottom
Caudal fin – tail fin
Caudal peduncle – the slender part of the body from the base of the anal fin to the start of the caudal fin
Chevron – V-shaped
Detritus – material from decomposing plants and animals
Diadromous – refers to fish that make migrations between the sea and fresh water, may be in either direction and not necessarily related to spawning
Dorsal fin – an unpaired fin on the back; there may be up to 3 dorsal fins
Endemic – native and restricted to a particular geographic area
Ephemeral – water bodies that are not permanent
Estuary – the area at the mouth of a river that is affected by the ebb and flow of tides
Family – a taxonomic category containing a single or many genera
Fecund – fertile; producing large numbers of eggs
Fin ray – a bony rod supporting a fin. Rays are usually branched into two halves (side by side), are often segmented, and usually flexible
Fin spine – a bony rod supporting a fin that is not divided unto two halves. Often spines are stiff and sharp
Forked – refers to the posterior margin of the caudal fin – deeply indented
Fragmented – broken up
Genus – a taxonomic category containing a single or many species
Gill opening – the exterior opening of the gills – located just behind the head. Gill openings may be covered by a bony plate (the operculum) or soft flaps of skin
Gill membrane – a fleshy flap on the back of the operculum used to allow the gill opening to be closed
Gonopodium – a specialized part of the anal fin in male Poecilidae that is used to transfer sperm to female fish
Indigenous – native but not restricted to a particular geographic area
Kype – an upward turning hook that develops on the lower jaw of some male Salmonidae during spawning
Larvae – newly hatched young
Lateral line – a series of pores in the skin along the side of the fish, usually about halfway down the side
Nocturnal – active at night
Non-diadromous – fish that do not make migrations between the sea and fresh water
Pectoral fins – paired fins (one on either side of the body) located just behind or below the gill openings
Pelagic – living in open waters near the surface
Pelvic fins – paired fins (one on either side of the body) located on the ventral side of the fish between the head and the vent. Pelvic fins are not always present, e.g. mudfish
Phytoplankton – tiny floating aquatic plants (algae)
Posterior – the rear or tail end
Redd – a nest excavated on the substrate by female Salmonidae
Rounded – refers to the posterior edge of the caudal fin – a convex curve
Scales – thin, overlapping plates of a hard substance that protect the skin of fish. The easiest way to tell if a fish has scales is to run your finger along the side of the fish from back to front. If the fish feels smooth and slippery, it has no scales or the scales are embedded within the skin; if it feels rough and your finger catches, then it has external scales.
Scientific name – the taxonomic name for a species, consisting of two words, the genus and species
Serrated – notched like a saw blade
Species – a taxonomic category of individuals or populations capable of breeding among themselves, but not usually with other individual or populations
Substrate – the bottom or material making up the bottom of a river or lake bed
Taxonomy – the study of the classification of living organisms, including rules and systems of naming organisms
Vent – the posterior, external opening of the gut; the anus
Ventral – the lower surface of the body
Vertebrae – the individual bones or segments that form the backbone. Vertebral count refers to the number of bones found in the backbone
Whitebait – juvenile fish of the Galaxiidae family; generally used in reference to the diadromous species only