Every child who has fished from a New Zealand wharf has caught a spotty. Small, inquisitive, and extraordinarily willing to take a bait, the paketi is the fish that introduces most New Zealanders to the concept of fishing, and then to the concept of unwanted bycatch, because it is too small to keep and too persistent to ignore. It will take a hook baited for snapper with the confidence of a fish that has never considered the possibility of consequences. Notolabrus celidotus is the most common wrasse in New Zealand, endemic throughout the country from Northland to Stewart Island, and found on every rocky reef with sufficient structure and algal cover. Females are olive-brown with pale spots and a white belly, which is the colour scheme responsible for the common name. Males are a different proposition entirely: vivid orange-green or turquoise, with iridescent markings and a far more conspicuous presence on the reef. The two sexes look different enough that early naturalists classified them as separate species. That is because they were the same individual at different stages. Spotties are protogynous hermaphrodites, beginning life as female and, if large and dominant enough, transitioning to male at around 13 to 19 centimetres and three to four years of age. The transition involves a complete remodel of the colour pattern, the hormonal system, and the behaviour. Terminal-phase males establish territories, maintain harems of roughly twenty females, and aggressively defend both from rival males. Initial-phase males, smaller and female-coloured, use a different tactic: infiltrating spawning events by mimicking females convincingly enough to pass inspection. Both strategies produce offspring. The biology of sex change in the spotty is well documented enough that the species has become a standard laboratory model for studying sequential hermaphroditism in vertebrates. Diet is benthic and opportunistic. Those strong teeth are designed for prising invertebrates from rock surfaces and kelp holdfasts rather than chasing prey in open water. Amphipods, small crabs, molluscs, and worms are the primary items, picked off reef surfaces with the deliberate, head-down focus of a bird working a lawn. The spotty is not a food fish. It is too small, and those who have eaten one report results that do not encourage repetition. Its value is ecological, as a common and abundant reef invertebrate predator, and scientific, as a model organism that has proved considerably more cooperative in captivity than most reef fish manage to be.