Tropical Fish Research
Stress in Fish
In a recent article in Tropical Fish Hobbyist, a careful look at stress in fish was printed. Stress Treatment for Fish looks at the ways that the studies of stress in fish can be a way to look more carefully at stress in humans as well.
The reasons for stress in a fish can be quite diverse. There seems to be a link in the research between the way stress is controlled in humans and fish. As seems more and more common, the fish that was used in the studies was the Danio rerio, Zebra Danio in most cases and the results are quite revealing in parallels between the two species.
Chronic stress can lead to depression and anxiety in humans. Scientists working with Herwig Baier, Director at the Max Planck Institute of Neurobiology in Martinsried, recently discovered a very similar link in fish. Normally, the stress hormone cortisol helps fish, as in humans, to regulate stress. Fish that lack the receptor for cortisol as a result of a genetic mutation exhibited a consistently high level of stress. They were unable to adapt to a new and unfamiliar situation. The fishes’ behaviour returned to normal when an antidepressant was added to the water. These findings demonstrate a direct causal link between chronic stress and behavioural changes which resemble depression. The findings could also open the door to an effective search for new drugs to treat psychiatric disorders.
Transportation Stress in Fish Studies
Anytime fish are moved, they are placed under stress. The reaction of Zebras to this transportation stress in fish was seen to be quite predictable – the fish did not move very much for a few minutes but healthy specimens sis start to recover and begin to explore their surroundings quite rapidly.
There are genetic mutations where stress in fish is much more pronounced. These fish will take quite a bit longer to move to the exploration phase and seem to be quite inhibited. Fish that are severely debilitated will even sink to the bottom of the tank and remain there. In essence they are showing signs of clinical depression. What is especially interesting is that when this stress in fish is treated with derivatives of Prozac style drugs added to the water, the fish recover relatively rapidly and begin to swim and explore. This seems to indicate that there are physiological reasons for differences ion the ability to cope with stress in fish even within the same species.