The simple clownfish is smaller than a human fist. But when a diver approaches his underwater house, between the tentacles of a sea anemone on the coral reefs in the world, the little orange creature stands up and adopts a fierce protective attitude.
"They are pretty aggressive fish," says Karen Burke da Silva, a marine biologist at the University of Flinders in Australia.
"If you come close to a clownfish, it will come out of its anemone and try to bite you … it's not logical."
Despite its territorial nature, clownfish is one of the easiest to recognize coral reef people.
The orange-and-white striped species became famous through the popular animated film "Finding Nemo" from 2003. The film told the story of an adult clownfish looking for his son Nemo, after a diver has captured him from the wild. But the success of the box office had unintended consequences.
Da Silva says that the film caused a wave of demand for pet-clownfish.
"The film portrays a very different message, namely" do not take Nemo out of the sea. "And yet people reacted very differently," she says.
"The places where they got that fish were actually from the wild," she explains, adding that overfishing has led to local extinction in some places.
Da Silva is co-founder of an initiative called "Saving Nemo." It works together with schools to promote the conservation of clown fish and to teach students about marine habitats.
At the Belgian Gardens Primary School in the city of Townsville in Australia, volunteers participate in the breeding of baby clown fish.
"We breed them so that we can give fish we can breed to people who want clownfish, so they do not have to get them out of the wild," explains 11-year-old Imogen Everson
She and her classmates clean tanks, cultivate the artemia – or sea monkeys – that are used to feed clownfish, and they follow the growth of the emergent clownfish.
In one of the tanks, she identifies a small cluster of what looks like bubbles that run along the inside of an earthen pot. They are clownfish eggs.
"The father, the smaller clownfish, will always check them … and give them oxygen," says Everson.
Ryan Pedley, the director of the school, says captive brined anemone fish are later traded to pet stores for the necessary aquarium supplies to keep the program running.
"It is another way to immerse our students in reef ecology," says Pedley.
"The children do not really have to visit the reef, they can do their part by breeding clown fish in captivity and donating them to the fish shops."
Coral reef is dying
Marine biologists say that in recent years the clownfish has been confronted with a newer, potentially more destructive challenge: climate change.
Rising temperatures around the world are bleaching and killing the coral reefs and sea anemones with which clown fish share a symbiotic relationship.
In fact, in 2016 and 2017, consecutive marine heat waves around half of the coral have been killed on the Great Barrier Reef in Australia, the world's largest reef habitat.
"If it [clownfish] can not find a sea anemone to call home and get protection, we can see that the population is dying ", says Jodie Rummer, a marine biologist at James Cook University.
Rummer's research has concluded that if sea temperatures rise between 1.5 and 3 degrees Celsius, coral reef fish lose between 40 and 70% of their performance, including swimming, feeding and breeding.
The scientific consensus concludes that global temperatures are about 1 degree warmer than in the pre-industrial era at the end of the 19th century. Scientific organizations such as NASA predict that the planet will continue to heat up in the coming decades as a result of increasing carbon dioxide emissions.
Rummer claims that clown fish and other marine species will probably need more drastic help than breeding programs for breeding grounds.
"The way to protect them is really a very big solution: that's kind of ending our dependence on fossil fuels, which is directly related to global warming," she says.