Eel (Shortfin eel) Anguilla australis

Kingdom: Animalia
Phylum: Chordata
Class: Actinopterygii
Order: Anguilliformes
Family: Anguillidae
Genus: Anguilla
Species: A. australis
Binomial name: Anguilla australis
Common name: Shortfin eel, Short-finned eel

Anguilla australis is one of the 15 species of eel in the family Anguillidae. It is native to the lakes, dams and coastal rivers of south-eastern Australia, New Zealand, and much of the South Pacific, including New Caledonia, Norfolk Island, Lord Howe Island, Tahiti, and Fiji. They are found throughout New Zealand and on Chatham and Stewart Island

The Shortfin eel body is long and snakelike, roughly tubular and the head is small, with the jaws reaching back to below the eye or further. There are no markings of note, but the underside is pale, often silvery, and the fins greenish. When full grown, they reach about 90 cm. The short-finned eel has a typical regeneration time of 15 to 30 years for females and it reaches a maximum size of about 1.1 m and 3 kg. Males tend to be slower growing and reach a smaller adult size. They are carnivorous, eating earthworms, crustaceans, fish, frogs and even small birds mainly ducklings.

Anguillid eels are undifferentiated gonochoristic fish. This means that the sex of the animal is determined from an undifferentiated gonad. Differentiation then occurs and an eel becomes male or female, and this is generally correlated to the size (20.0-22.5 cm) of the animal not its age.

They differ from longfin eels in the length of their dorsal fin. In shortfin eels, the dorsal and anal fins are the same length so the ends are almost adjacent when the fish is viewed side-on. Shortfin eels usually have a silvery belly compared to a yellowish one on longfins, but colours can vary considerably, even (rarely) yellowish.
Generally, shortfin eels are found at lower elevations and not as far inland as longfin eels, but they are still able to climb large obstacles such as waterfalls when they are young. They are often very numerous in lowland lakes, wetlands, and streams and shortfin eels form the basis of the commercial eel fishery that has existed for over 20 years in New Zealand.

Shortfin eels are our most tolerant native fish species. They survive environmental hazards like high water temperatures or low dissolved oxygen concentrations. That means they can live in habitats where other species cannot survive. Their ability to live almost anywhere might explain why eels are so familiar to New Zealanders and why they were such an important food resource for Maori. (Some text thanks to NIWA)

The difference between Longfin and shortfin eels

1-Difference between eels.JPG  

1-Shortfin eel.jpg 

Thanks to Wikipedia for text and information: