Nature can surprise in different ways, either with newly discovered species or with some that can change sex as they age. This is the case of the New Zealand fish, which can change from female to male as part of a process of changes in social hierarchy.
According to a study from the University of Otago in New Zealand, the New Zealand spotty fish, also known as paketi, changes sex when another dominant spotty fish is removed from the group.
It was also discovered that these fish form linear dominant hierarchies based on their size. This means that the larger ones dominate the smaller ones. Moreover, it is stated that the dominant behavior that accompanies this change does not indicate a typical female to male behavioral modification.
In this sense, it was shown that the fish that reached dominant positions showed significant differences compared to fish from other ranks. This served to highlight the importance of social context in the individual behavior of this species, revealing that they can adapt to changing social environments.
A study that opens doors to new research
The study focused on the neuronal mechanisms behind the social interactions of these species revealed that decision-making is involved in establishing dominance.
However, experts stated that this finding can be applied to other fish species that change sex, where social dominance is also important as a trigger for this change.
Furthermore, they argue that this finding could benefit aquaculture and open-water fishing, as many commercially valuable fisheries depend on sex change in some species, such as blue cod.
The New Zealand spotty fish changes sex when ascending in the social scale. Photo: Reef Live Survey.
A stealthy inhabitant of New Zealand streams
The New Zealand spotty fish is a freshwater species that mainly inhabits clean rivers and streams in New Zealand. It is distinguished by its elongated, semi-transparent body covered with small golden spots that give it natural camouflage against predators.
One of its most striking characteristics is its ability to adapt to changing environments. During its life cycle, it migrates between freshwater and saltwater, as its offspring, known as “whitebait,” are born in the sea and swim up rivers to grow and reproduce. This migratory behavior is crucial for its survival.
Despite its small size—rarely exceeding 10 centimeters—this fish plays a key role in aquatic ecosystems, as it is part of the diet of birds and larger fish. However, pollution and river modifications have placed it at
