This is one of the classic questions that can appear to us in a trivial one and surely we will be baffled in the moment in which we know the answer.
And yes, the fish of the sea are capable of having and have to drink water in order to survive. The reason for this is that in the sea we can find an enormous amount of salts that have a density of approximately 35 g per liter. The problem is that at the moment the salts are separated in water, they form and positive ions and negative ions.
The body of the fish consists mainly of water, as well as some substances like sugars, proteins and fats; However, they also have a certain amount of salts that are dissolved throughout all of their bodily fluids.
Many sea animals have a very low salt concentration in their body and for this reason they need to live around a high saline concentration in their environment.
However, the problem with the fish of the sea is that the osmotic process can not be fulfilled in the proper way. So that you can find out: if we are in an environment where two volumes of water have different concentrations and is brought into contact, the water that has less salt begins to flow to the side where the water has the highest density.
As the water of the sea is much saltier than the liquid that the fish have inside, these little by little they discover that the water of its interior is escaping by its gills.
In conclusion, the fish can die dehydrated precisely because the internal balance of mineral salts is not adequate.
To avoid that this can happen, the fish has to drink water. However, another problem you have to overcome is that the medium you are in will only provide you with sea water that will have a high concentration of salt. Fortunately, we can be sure that thanks to your body has two methods to eliminate this salt: through the gill epithelium and urine.
If they did not have these natural means, in all likelihood they could not live the time they are currently living.
Credits: Interesting news