Saltwater fish loses salt through their skin, while freshwater fish tend to absorb it. Water is always trying to reach equilibrium. Therefore, the salt moves from high concentration areas to low concentration areas. Since ocean water is very salty, saltwater fish will have a lower concentration of salt in their body compared to the water they swim in. As a result, most saltwater fish constantly lose water through their gills and skin.
In contract, freshwater fish will constantly absorb water through their gills and skin. Most freshwater fish and saltwater fish maintain a salt concentration in their blood of approximately 10 parts per thousand ppt , or 10 grams of dissolved salt per liter of water. Since freshwater fish swim in water with approximately 0.
On the other hand, since saltwater fish swim in water with approximately 35 ppt, the chloride cells in their gills are designed to pump salt out of the out of the fish. This process of controlling the flow of water across their body is called osmoregulation. Saltwater fish have hypotonic cells, which keeps the salt inside the cells. Therefore, when saltwater fish are placed in a salt deficient freshwater environment, water will rush into their cells.
This will cause the fish to die. Freshwater fish have a higher salt concentration in their body than the water around them. Therefore, they are constantly working to keep the salt in their body, and expel the water out of their body.
If the freshwater fish is placed in a saltwater environment, the salt would flood into their body at a high concentration. This would dehydrate the fish, and kill the fish. Fish that are able to live in both freshwater and saltwater are called euryhaline fish. These highly adaptable fish are able to migrate back and forth between the ocean and rivers. Euryhaline fish that spawn in freshwater and migrate to the ocean are called anadromous fish. An example of anadromous fish are salmon.
Euryhaline fish that spawn in the ocean and migrate into bodies of freshwater are called catadromous fish. Examples of catadromous fish are North American eels and European eels. While euryhaline fish are adaptive species, they do require a acclimation period to allow their bodies to adjust to the different salinity levels.
These fish may gradually acclimate their body in estuaries, which is a region where freshwater and saltwater mix. Fish that are only able to live in a narrow range of salinity are known as stenohaline species. The majority of fish are stenohaline species.
Unlike euryhaline species, stenohaline fish are unable to adapt to different salinity levels. For example, goldfish can only live in freshwater and clownfish can only live in saltwater. Both fish are stenohaline species. When choosing between a freshwater aquarium setup and a saltwater aquarium setup, it is important to realize the difference in level of difficulty and level of care required.
In general, freshwater fish are hardier due to their adaptive nature. Saltwater typically refers to water found in oceans and seas, and freshwater is found in lakes, rivers, ponds, and streams. Freshwater only accounts for less than 3 percent of all the water on earth, but ironically, freshwater fish make up almost half of all fish species.
Gourami fish are among the more popular fish for freshwater aquariums. The way fish take in and eliminate water is perhaps the most significant difference between saltwater and freshwater fish. Both types of fish need salt in order to survive, but the way their bodies function is actually the opposite of what one may expect.
In order to prevent dehydration, it takes in a large amount of water and secretes the salt through its gills. But there are differences in taste, bone structure and nutrients between freshwater fish and saltwater fish. Knowing the differences between freshwater fish and saltwater fish can help you make the right choice for you at the seafood counter. The taste difference between freshwater fish and saltwater fish is the most important for many people.
If you enjoy fish that have the flavor of the ocean, saltwater fish are the best option for you. In contrast, freshwater fish do not have a briny flavor and tend to have a milder flavor profile. For example, freshwater perch is popular for homemade fish sticks and fish tacos because of its mild taste.
The most notable distinction between saltwater fish and freshwater fish when you are preparing them is their bone structure. From the outside, they may look the same but when you open them up to debone them you will notice the difference.
Saltwater fish tend to have larger bones and tend to be easier to debone properly.
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