Fish do not get thirsty in the way humans do, but they absolutely do need and regulate water in their bodies.

What “thirst” means for fish

In humans, thirst is a conscious feeling that pushes us to seek and drink water. Fish, however, live surrounded by water, and their water balance is controlled automatically by their bodies rather than by a conscious desire to drink. Current scientific thinking is that fish do not “feel” thirsty as a sensation like we do, even when they are drinking.

Freshwater fish

Freshwater fish have saltier body fluids than the water around them. Because of osmosis, water constantly flows into their bodies through their skin and gills, so they do not need to drink; instead, they get rid of extra water by producing lots of dilute urine to keep their internal salt levels stable.

Saltwater fish

Saltwater fish swim in water that is saltier than their blood. Water tends to leave their bodies, which would dehydrate them, so they actively drink seawater and then pump out excess salt through special cells in their gills and in small amounts of salty urine.

So, can fish “get thirsty”?

Biologists often answer this question with “no, not like us, but it’s complicated.” Fish clearly need water balance to survive and have strong automatic reflexes to take in or expel water and salts, yet there is no good evidence that they experience a conscious craving for water the way land animals do when they feel thirsty.

Information gathered from public forums or data available on the internet and portrayed here.