The common smelt’s scientific name is Retropinna retropinna. There are two New Zealand species in the Retropinnidae family, the common smelt and Stokells smelt.
Smelt can be distinguished from other species by their easily dislodged scales, and by the presence of the adipose fin, a small fleshy lobe on their back between the dorsal fin and the tail.
They also have a distinctly forked tail and a strange, strong cucumber smell.
The common smelt is found around the sides of lakes or in streams or estuaries, where it lives in a large group and swims around looking for insects that have fallen into the stream. It is a shiny silver colour with purple along its sides and transparent fins.
After it lays its eggs, the smelt will die and its young swim out to sea. They stay out at sea until they are ready to lay their eggs, by the next summer. They then come back to the river, lay their eggs and die like all their ancestors have done before them. Common smelts live in flowing and still water, and there are both diadromous (sea-going) and non-diadromous (land-locked) populations located througout New Zealand.
Did you know? Of all the freshwater fish that live in New Zealand, smelt are one of the most sensitive to pollutants. The presence of smelt usually indicates that the water quality is suitable for most other fish.