Goldfish

Distribution in the Styx River:

Surprisingly well distributed.  Goldfish have been Identified from isolated gravel pits and ponds throughout the catchment. Identified from Bottle Lake, a pond in the Burwood pine plantation, Ashby Pit, and isolated ponds alongside Smacks Creek.  Most of these would represent deliberate, if not uninformed, attempts to establish populations, possibly for aesthetic reasons, or for aquatic weed control (McDowall 1990).

Biology

The goldfish is capable of living in aquatic habitats which contain little oxygen. They spawn amongst aquatic weeds and eggs hatch in about a week. The young are provably predated upon by eels, which are often pond inhabitants. Goldfish live on both plant material and invertebrates. In the wild, goldfish lose their bright gold colour, and become more bronze, as depicted in the photo at the top of the page.  The largest goldfish in the catchment were recorded at approximately 150 mm in length.

A single record of a tench (Tinca tinca) , a species from the same Family as the goldfish (i.e. F. Cyprinidae) is also present in the Ashby Pit pond (NZFFDB 2008), probably an introduction in an attempt to establish a coarse fishery in this water body. These fish are an acclimatised sports fish in Northland.

References

• McDowall, R. M. 1990: New Zealand Freshwater Fishes: A Natural History and Guide. Auckland, Heinemann Reed. 553 p.
• NZFFDB 2008: Archives of the New Zealand Freshwater Fish Database.National Institute of Water and Atmospheric Research, Wellington.