Salmon is frequently live in both rivers and oceans.

Freshwater fish have gills that function to diffuse water (not allowing impurities inside) while ensuring bodily fluids remain inside the fish. Freshwater fish have large, well-developed kidneys that are able to process vast quantities of water.

Saltwater fish lose large quantities of internal body fluids through their gills because of osmosis. Since saline water is less dilute than the internal fluids of the fish, the saline water rushes in to replace the internal fluids in an effort to form an equilibrium. They replace lost water by consuming large quantities of saltwater.

Freshwater fish include catfish, charr, cisco, mooneye, gar, shiner, trout (apache, blueback, brook, brown and cutthroat), sunfish, pike, salmon (pink, coho, chum, Chinook and altantic) and whitefish.

Saltwater fish includes albacore, certain types of bass, bluefish, common dolphin, butterfish, eels, flounder, cod, marlin, mackerel, herring, shark, snapper, tuna and yellowtail.

Reference ->

Natasha Gilani

https://sciencing.com/different-freshwater-vs-saltwater-fish-6307253.html

Salmon is frequently live in both rivers and oceans.

Freshwater fish have gills that function to diffuse water (not allowing impurities inside) while ensuring bodily fluids remain inside the fish. Freshwater fish have large, well-developed kidneys that are able to process vast quantities of water.

Saltwater fish lose large quantities of internal body fluids through their gills because of osmosis. Since saline water is less dilute than the internal fluids of the fish, the saline water rushes in to replace the internal fluids in an effort to form an equilibrium. They replace lost water by consuming large quantities of saltwater.

Freshwater fish include catfish, charr, cisco, mooneye, gar, shiner, trout (apache, blueback, brook, brown and cutthroat), sunfish, pike, salmon (pink, coho, chum, Chinook and altantic) and whitefish.

Saltwater fish includes albacore, certain types of bass, bluefish, common dolphin, butterfish, eels, flounder, cod, marlin, mackerel, herring, shark, snapper, tuna and yellowtail.

Reference ->

Natasha Gilani

https://sciencing.com/different-freshwater-vs-saltwater-fish-6307253.html

Differences in Nutrients

Freshwater fish and saltwater fish are quite similar when it comes to their nutritional content; however, freshwater fish may have a slight advantage. Lake fish are generally higher in calcium and monounsaturated and polyunsaturated fatty acids than ocean fish.

Even though ocean fish don’t absorb the sodium from the water that surrounds them, saltwater fish tend to have a much brinier, “fishy” taste than their freshwater counterparts. However, most freshwater fish lack this briny flavor, making it a milder option for those who aren’t big on tasting the flavors of the ocean.

Marine fish because of it's body composition

I think both fish fresh and marine fish are same but the marine fish is best becouse it is composition(salt ,menirals and vitamine)

Both have good taste but I think marine water fish have special taste better than fresh water and it is dependent on where we live closed to sea or freshwater, any way there are similar