Redfin Bully
Redfin bully (Gobiomorphus huttoni)
The bright red fins of an adult male redfin have to make this one of our most attractive freshwater fish. Although only males get this distinct colouration, the diagonal stripes on the cheeks make the redfin bully easy to identify. These stripes are visible in small bullies from about 30 mm in length.
Redfin bullies are strictly diadromous and do not establish land-locked populations. Thus, they tend to live near the coast even though they are very good climbers; populations above 5-m-high waterfalls have been recorded.
The juveniles enter fresh water in the spring and reach maturity about two years later. Spawning takes place in fresh water and after hatching the larvae are swept down to the sea. This diadromous habit means that they are widespread throughout the country and have been frequently recorded from Chatham and Stewart Islands. However, their preference for streams with large stable substrate means that they are rare along the east coast of the South Island above Oamaru, except for Banks Peninsula.
The redfin bully was recognized as a distinct species as early as 1894, but it has had many name changes over the years. The present specific name huttoni honours one of New Zealand's early biologists, Sir Frederick W. Hutton, who was a director of the Canterbury Museum from 1892 to 1905.
