Sandager's wrasse

Lore & Background

The fish was named after Andreas Fleming Stewart Sandager, a lighthouse keeper in New Zealand who collected the first specimen. The scientific name uses the specific epithet sandeyeri, and a proposal was made in 1927 to change it to 'sandageri' on the theory that the original description constituted a misspelling. However, in 2011 it was shown that 'Sandager' was also spelled 'Sandeyer' at that time, and thus the original spelling of the scientific name should stand.

Sandager's wrasse lives in small shoals consisting of one male and several attendant females and juveniles. In the presence of the male, all juveniles grow into females, but when the male dies or is removed from the shoal, the group's dominant female undergoes physiological changes to convert herself into a male. The male fish has a deeper body and differs significantly in colouration; for example, the male has very distinctive bands, whereas the female is paler in colour and only has two dark spots.

Reader's Guide

Sandager's wrasse is notable for its presence in the aquarium trade and its distinctive social structure, which involves sequential hermaphroditism. The species' range across the southwestern Pacific, from Australia to New Zealand and the Kermadec Islands, and its occurrence on reefs to depths of about 60 meters, make it a familiar inhabitant of these waters. The etymology of its scientific name reflects a historical spelling dispute: originally named with the epithet sandeyeri after lighthouse keeper Andreas Fleming Stewart Sandager, a 1927 proposal to correct it to 'sandageri' was later resolved in 2011 when evidence showed that 'Sandager' was also spelled 'Sandeyer' at the time, preserving the original spelling. The species' behavior, documented in 2012, describes a haremic social system where a single male controls a group of females and juveniles, and upon his removal, the dominant female transforms into a male. This reproductive strategy, along with the sexual dimorphism in body shape and coloration—males having deeper bodies and distinctive bands, females being paler with two dark spots—underscores the species' biological interest. Its inclusion in the aquarium trade further extends its significance beyond natural history.

Did You Know?

• A 1927 proposal to change the scientific name to 'sandageri' was rejected in 2011 because 'Sandager' was also spelled 'Sandeyer' at the time.
• When the male of a shoal dies or is removed, the dominant female undergoes physiological changes to become male.
• Males have a deeper body and distinctive bands, while females are paler with only two dark spots.