When we discuss animal depression, it is commonly in reference to the feline and canine species, but not normally fish! It seems a little strange that a fish could be suffering from depression when the term is defined as “feelings of severe despondency and dejection.”
However, throughout numerous studies, it has been shown that fish, in fact, exhibit multiple symptoms of depression the same as any other animal or even humans do. A lethargic fish that tends to float through their bowl, hovering on the bottom and those that show signs of a decreased appetite can be deemed depressed.
According to some of the scientists who have conducted a variety of studies using fish as subjects, fish can actually be a beneficial model to understanding depression in not only animals but also humans due to similar neurochemistry makeups. The special bonds between pets and their owners can lead to answers regarding depression and the effects on relationships when studied properly.
The effectiveness and side effects of anti-depressant medication were similar enough to fish and humans that it leads to both new answers and new questions. Studies are currently being conducted using fish, in particular, zebrafish – a small fish that is found in tropical freshwater, to develop more effective anti-depressant medication. Zebrafish are quickly becoming the go-to fish for clinical studies because of its transparent body and rapid reproductive rate. They also share approximately 70% of genetic makeup with humans.
Fish are generally thought to be simple organisms with a sole purpose in mind, but the reality is the brain functions and moods can vastly differ from species to species. A fish can be diagnosed as depressed almost instantaneously when introducing it to new surroundings or a differently decorated bowl. A fish that sinks to the bottom and allows the currents of the water to move it from place to place is most likely depressed. An inactive fish that loses interest in everything from mealtime to exploring can be classified as depressed.
A lack of stimulation and insufficient oxygen is most likely the cause of fish depression, according to Victoria Braithwaite. Braithwaite is a professor of fisheries and biology at Penn State University and has concluded that fish are naturally curious to anything in their view and a lack of this exploration is a sign that something is wrong.
Some scientists argue that instead of depression, fish show more anxiety-based symptoms. Fish and other animals are unable to communicate exactly how they are feeling, so findings are based on previous interactions with the same fish or fish that have been given safe dosages of new medications.
As with humans, interactions can vary from species to individual fish of the same family. So next time you are contemplating a fish as a household pet, go the extra mile and invest in a good sized fish tank with a variety of plants and structures to stimulate your fish and sit back to enjoy the show!