There are fish that live in freshwater like neon tetra, betta fish, angelfish fish etc. These fish cannot live anywhere else other than freshwater. Similarly, there are some fish that live only in salt water for instance, blue fish, tuna, rockfish, sea perch etc. The saltwater fish are also called marine fish or sea fish. The fresh water fish and the salt water fish both live in their respective environments i.e freshwater fish in the freshwater and saltwater fish in the salt water. But, the question that arises here is can a saltwater fish live in the freshwater and similarly can a fish water fish live in saltwater?
Can Salt Water Fish Live in FreshWater?
The answer is “NO”, it is not possible for a freshwater fish to survive in water where there is high concentration of salt. Similarly, it is not possible for a saltwater fish to survive in the water where there is low concentration of salt. But, interestingly, there are some fish that can adapt to the fresh water despite them being saltwater fish and vice versa.
Why Can a Freshwater Fish Not Live in Saltwater?
The freshwater fish normally lives in water where there is low concentration of salt. So, exposure to the environment that has high levels of salt is what freshwater fish cannot tolerate. This is mainly because of the “osmosis” process that says the molecules move from the fluid with low concentration to that of high concentration. Fish have a semipermeable membrane that has small holes that help water molecules to pass in and out. The small holes are large enough to pass the molecules of water but they do not allow salt or sugar molecules to pass.
When a freshwater fish enters the saltwater, the water molecules move from the body of the fish to the external water. This causes dehydration in the body of the fish and the fish eventually dies. So, it is impossible for almost all of the freshwater fish to survive in saltwater.
Why Can a Saltwater Fish Not Live in Freshwater?
Saltwater fish have the chemistry that makes them live and survive in the water in which there is a high concentration of salt inside it. This is also because of the “osmosis” process as discussed earlier. The water molecules move from the external environment to the body cells of the fish causing them to bloat. So, when a saltwater fish is placed in an environment where there is low concentration of salt, it cannot survive and eventually dies.
Fish That can Survive in Both Freshwater and Saltwater
There are some kinds of fish that live in both freshwater as well as saltwater because they have the capability to maintain a certain level of sanity in their bloodstream. These fish include Catfish, Salmon, Monodactylus, Atlantic stingray and Bull shark.
The Bottom-Line
It is not possible for a saltwater fish like blue fish, tuna, rockfish and sea perch to live in an environment where the water has low concentration of salt and similarly the fresh water fish like neon tetra, betta fish and angelfish fish can also not survive in the water that has high concentration of water. But there are rarely some types of fish that can survive in both the freshwater and the saltwater, for instance, catfish, salmon fish and bull shark.
