There are approximately 86 species of goatfish belonging to the Mullidae family and they are distributed throughout six different genera. In NZ only 3 species are found, the blackspot goat fish, the bar-tailed goatfish and then the NZ Goatfish otherwise known as Upeneichthys lineatus or Red Mullet which is the species we will focus on.
The NZ Goat fish is a vertebrate that grows to around 40cm in length. They have 2 barbels (long white or yellow appendages) attached to their chin which are used to detect life and food below the sand.
The life span of this fish is unknown. At a year old they are roughly 13-15cm in length then at 2 years their growth rates slow and they will have grown only a few cm more in that time. They spawn by releasing sperm and eggs into the water column and separate immediately afterwards. Dominant males patrol their spawning territories keeping other males out sometimes getting violent and courting new females that venture in.
They are common around the north island and northern parts of the South Island. Living at depths from 0-100 metres they are often found in either rocky reef areas or sandy patches close to reefs most likely to have originated in Australia as the first sightings were recorded in Sydney.
Goat fish are predators, small Goat fish eat during most of the daylight hours for prey such as worms and crustaceans. Larger specimens eat blennies and triple fins and have been observed hunting in groups and using their barbels to herd the prey where it can be caught easier.
They are not a target species commercially however they are edible and reportedly good eating and as such can be targeted by recreational fishers with small hooks or by spearfisherman. Ancient Romans saw them as a status symbol and would serve them alive to observe the change in colour at death.
They are one of the most abundant larger reef fish and have been estimated at a population of 10000 per square kilometre in Eastern Northland. The population is healthy and the species is not threatened.
Of the sites that we frequent I see Goatfish on nearly every dive done in the leigh area as long as you get out close to the reef. Mathesons Bay is a clear example. Here at 14 metres the rocky reef and kelp forest gives way to sand patches with sponge life that act as resting stations for groups of up to a dozen Goatfish of differing colours.
Goatfish have the ability to rapidly change colour, and many species adopt a pale coloration when resting on the sand to blend with the background and become less visible to predators. These changes in color are reversible phenotypic (The physical appearance or characteristic of an organism.) changes and happen within seconds many times during the lifespan of an individual. They get the name red mullet from the colour change brought on at death to a hue of red.
