Torrent fish
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| Cheimarrichthys fosteri Haast, 1874 |
The torrent fish, Cheimarrichthys fosteri, is the only member of the genus Cheimarrichthys which in turn is the only member of the family Cheimarrichthyidae. It is found only in New Zealand, in stony rivers and streams all around the North and South Islands. It grows to a maximum length of 15 cm.
The torrentfish lives in the swift whitewater rapids of stony rivers and streams, and adaptations to enable it to live in this environment include a flattened head, large pectoral fins which help it to anchor on the riverbed, raised eyes, and a ventral mouth. Despite its skill at living in swift water however, the torrentfish is not a good climber and only penetrates inland in river systems where the gradient is relatively low.
Like many of New Zealand’s freshwater fish, the torrentfish is amphidromous and undertakes migrations between the sea and fresh water as part of its life cycle. Juvenile torrentfish enter fresh water in spring and autumn, and after a few weeks in the estuaries, begin moving upstream to the adult habitat. The adults continue to move slowly upstream, with the largest and most inland fish being the females and those in the lower reaches predominantly males. The spawning behaviour is unknown.
[edit] References
- "Cheimarrichthys fosteri". FishBase. Ed. Ranier Froese and Daniel Pauly. March 2006 version. N.p.: FishBase, 2006.
- NIWA June 2006
