This is a guide for identifying what family a fish is in, but to go futher and identify the species, you need to use our ID guides and keys.
Start at the top and work your way through the choices in the table below. In this key, we have relied on obvious external features and have tried to avoid using technical terms. There are a few features you might not be familiar with - look in the glossary for a definition. Use the Fish Finder if you have a common name for the fish you want to see.
Key to the Families
| Item | Characteristic | Next |
|---|---|---|
| 1 | Scales absent or embedded | go to item 2 |
| Scales present | go to item 5 | |
| 2 | Seven gill openings on each side of head | Lamprey (Geotriidae) |
| One gill opening on each side of head | go to item 3 | |
| 3 | Fish long and thin (snake-shaped) | Eels (Anguillidae) |
| Fish not long and thin | go to item 4 | |
| 4 | Barbels present around mouth | Catfish (Ictaluridae)* |
| No barbels | Whitebait and mudfish (Galaxiidae) | |
| 5 | Fish flat and plate-shaped | Flounder (Pleuronectidae) |
| Fish not flattened | go to item 6 | |
| 6 | Tail rounded | go to item 7 |
| Tail not rounded | go to item 9 | |
| 7 | One dorsal fin | Live bearers (Poeciliidae)* |
| Two dorsal fins | go to item 8 | |
| Three dorsal fins | Estuarine triplefin (Tripterygiidae) | |
| 8 | Gap present between dorsal fins | Bullies (Eleotridae) |
| No gap present between dorsal fins | Dart Goby (Microdesmidae) | |
| 9 | Adipose fin present | go to item 10 |
| Adipose fin absent | go to item 11 | |
| 10 | Lateral line present | Trout and salmon (Salmonidae)* |
| Lateral line absent | Smelt (Retropinnidae) | |
| 11 | One dorsal fin | go to item 12 |
| More than one dorsal fin | go to item 13 | |
| 12 | Head slightly flattened with a dark band between the eyes | Torrentfish (Pinguipedidae) |
| Head not flattened | Carps (Cyprinidae)* | |
| 13 | First dorsal fin with 4 spines | Mullet (Mugilidae) |
| First dorsal fin with more than 4 spines | Perch (Percidae)* |
* indicates the the families of introduced species.