Crans’ Bully

StellaMcQ, CC BY-SA 4.0, via Wikimedia Commons

Gobiomorphus basalis – tītarakura, Kōpū, Kōpūtea, – Endemic to NZ

The Crans Bully fresh water fish

The Crans’ Bully is one of seven Bully species found in New Zealand, the following four are found in Northland;

• Common Bully or Gobiomorphus cotidianus,
• Giant Bully, Kōkopu or Gobiomorphus gobioides,
• Bluegill Bully or Gobiomorphus hubbsi,
• Redfin Bully or Gobiomorphus huttoni.

All species of Bullies are endemic to New Zealand.

Crans bully In the Tangihua Forest

The Crans’ Bully or Gobiomorphus basalis can be found in the rivers of Northland’s Tangihua Forest.

Crans bully Physical Description

Bullies have rounded tails, two dorsal fins, a blunt head and a stocky body. The largest Crans’ Bully identified was 92mm long.

The Crans’ Bully is brown with irregular dark and pale patterns on their sides. Males have an orange stripe along their backs that the female lacks. In spring the males turn from brown to black with an orange stripe, likely to help with attracting females.

Crans Bully Behaviour

The Crans’ Bully can sometimes be recognised by their habit of sitting on the river bottom looking almost as if they were standing up on their forward fins.

Feeding

They have a darting method of swimming and usually remain on or close to the bottom of the river where they hunt for insects or small crab-like animals

Crans’ Bully life cycle

Crans bully do not migrate, remaining in the same stream for their lifetimes. Crans’ Bully mature at one year old and live to be three or four years old.

Adults spawn in spring and summer. The male finds a territory beneath a rock for the female to deposit a few thousand eggs. Multiple females may deposit eggs in the same nest prepared by the male. Several weeks after laying, the eggs hatch and the larvae stick together in the quite waters along the edge of the river until big enough to venture out on their own.

Distribution and Habitat

Crans bully are restricted to cobble and boulder rivers and streams and do not populate lakes, unlike other species of Bullies.

The Crans’ Bully is only found in the North Island from sea level to around 500m elevation. While found throughout most of the North Island, they have never been seen in the central North Island area. One theory is that they were wiped out by the Taupo eruption and haven’t repopulated that area as they do not migrate but remain in the same stream for their entire lifetime.

Threats and Conservation Plan

The Crans’ Bully is a non-threatened species.

References

It is very apparent that specific information has been shared online between many organisations. Attributing to the initial source is impossible. As much as possible we have used our own photo’s and the following websites have been used as sources for our information;

• Te Ara The Encyclopaedia of New Zealand,
• Wikipedia,
• DOC website, and
• T.E.R:R.A.I.N Taranaki Educational Resource: Research Analysis and Information Network.