Fish live in water, but do they ever get thirsty? Well, according to professor of fish physiology and aquaculture at the University of New Brunswick in Canada, Tillmann Benfey, the answer is that we don’t really know.
“It’s impossible to know what a non-human animal truly experiences,” he told How Stuff Works in an email interview.
It’s easy for us to tell when we’re thirsty. We first experience dry mouth, which can lead to fatigue and lightheadedness, and if we don’t drink water for a very long time, we can start craving it and become unable to think about anything else. But we can’t know if fish experience thirst. “I think of thirst as a cognitive response to hydration and it’s hard to get inside a fish’s brain,” Boston College assistant biology professor Christopher Kenaley told the outlet. One thing is sure — without hydration, fish would die. They use a process called osmoregulation to regulate water balance.
The process is not the same for saltwater and freshwater fish, but their bodies are perfectly capable to maintain a healthy relation of blood and salt at all times.