Cairns' marine biologist and manager, Paul Barnes, told ABC News that fish are curious animals that like to have new things to see and explore. Therefore, even the simple presence of people passing by the glass tank is a form of stimulation for them.
Although humans do not realize that fish can be seen outside the tank, they really like interacting with humans. They like to look at new faces and different colors on clothes worn by humans.
Like many other places, Cairns' waterway has been closed due to the COVID-19 pandemic and no tourists have visited, these fish have become negligent and disregard the surrounding environment.
Some fish species decided to take shelter in the dark corners of the tank. But the most notable of these is the Queensland spawning fish named Chang, which has been inactive for several weeks.
In that situation, the born giant management board hired another diver to swim with them, helping them overcome this pressure period. Cairns' CEO Daniel Leipnik said that reporting sharks - like dogs - like to pet.
"They are quite sensitive partly because their neural structure is similar to humans," said Julian Trumpman, a researcher at the University of Troy (USA) in a report published in NY Times in 2017.
Specifically, the levels of serotonin and dopamine (neurotransmitter) in fish also fluctuate - a sign similar to when people are depressed.
According to National Geographic, some aspects of depression can be measured in animals. One of its core symptoms is "anhedonia" - a lack of happiness - decreased interest in activities and loss of interest. The species is also likely to suffer from depression if they give up easily when encountering a stressful event.
Scientists also say that depression also manifests itself in animals through behavior. For example, when a child is depressed, just looking at their facial expression can also show that they are experiencing a "sad" mood.
