The world’s rarest fish is making a comeback, one ridiculous baby at a time

Behold, the rarest fish in the world! The red handfish, Thymichthys politus, is known from only two small patches of reef off the coast of Tasmania, where approximately 100 adults are thought to live. Habitat degradation and climate change have threatened them with extinction, but thanks to a breeding program they welcomed 21 young in 2023.

It was the second time red handfish had been successfully bred in captivity, and this led to a new generation representing a quarter of their wild population. Mother handfish care for their eggs until they hatch after about 50 days.

The target? To release these babies into the wild and strengthen the wild breeding population. However, before they can swim in the big blue, they must complete hand fishing school.

“Handfish school is an initiative funded by our supporters at the Foundation for Australia’s Most Endangered Species, and the aim is to develop ‘street smart’ skills for handfish raised in captivity,” handfish experts from the University of Tasmania, Dr Jemina Stuart-Smith and Dr Andrew Trotter told IFLScience.

“It involves introducing more complex habitats, other species and conditions that they are likely to encounter in the wild. It is essentially an acclimatization period that allows fish to learn natural behaviors such as finding food, seeking shelter, interacting with others of their own kind, and navigating the sea. The goal is to increase their chances of survival after release.”

Even reaching the egg-bearing stage was a daunting task for the Red Handfish team, because there’s still a lot we don’t know about the world’s rarest fish. For example, we have only recently learned how to tell apart males and females, which – as you can imagine – is useful to know when trying to mate potential mates. It’s also unclear exactly what environmental cues these fish use to know when breeding season is, but the team did observe two successful captive breeding events.

The difficulties don’t stop once the little bundles of joy hatch either. Coming out as fully formed 10 millimeter (0.4 in) handfish, feeding and caring for them is a challenge in itself.

“If you’ve never seen a handfish,” reads a quote on the Handfish Conservation Project website, “imagine dousing a toad in brightly colored paint, telling it a sad story and forcing it to wear gloves that are two sizes too big. ”

red handfish

The species’ ability to thrive in the wild depends on the specific habitat they need to reproduce.

Image courtesy of Tyson Bessell

If that doesn’t convince you of these critters, I honestly don’t know what will, but according to Stuart-Smith and Trotter’s accounts, they have great personalities too.

“They are quirky creatures that seem quite social. They are often found together in the wild. They are also ambush or ‘sit-and-wait’ predators that live on the seabed, so they spend most of their time standing still. But they also use fin displays in communication, which is often aimed at us humans, even though we don’t understand what they are trying to tell us!”

Recovery of the species will not be easy because unless the seaweed habitat they need to reproduce is restored and remains that way, the species will remain vulnerable. However, expanding their wild populations with recruits from the captive breeding and release program is a step toward bringing the red handfish back from the brink, with each ridiculous hatchling representing a step in the right direction.

“Handfish are part of the natural ecosystem and endemic to Tasmania,” Stuart-Smith and Trotter concluded, “so their loss would mean the loss of some of our unique natural values ​​and biodiversity.”

For more information about red handfish, visit the Handfish Conservation Project websiteor view the Institute for Marine and Antarctic Studies. The Red Handfish’s work is made possible by funding from the Foundation for Australia’s Most Endangered Species, the Australian Government’s Department of Climate Change, Energy, the Environment and Water (DCCEEW) and the University’s Institute for Marine and Antarctic Studies of Tasmania.

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