Yes, you can. however some stuff won't be usable for example gravel, because usually on saltwater aquariums is desirable a substrate that will help to maintaing PH, hardness and calcium on the water... But the tank itself can surely be used. With no restrictions other than space. usually saltwater aquariums require more water gallons per fish inch.
A saltwater fish tank can be half freshwater and all of the saltwater fish will live but not for very long.
Yes but you need to buy a saltwater filter to replace the freshwater one.
Certain freshwater fish can survive saltwater conditions; examples are black mollies, mono's and scats. All of these fish aren't truly freshwater or saltwater, they are Brackish. Brackish is between freshwater and saltwater, and so these fish are highly adaptable.
Yes saltwater marshes change daily ;not freshwater marshes
No. Not in the traditional definition of the tropical tank. A tropical tank is a freshwater aquarium. Regal Tangs are saltwater fish and go in a saltwater tank (marine aquarium).
yes just add salt!
No. Bettas are freshwater fish. Seahorses are saltwater.
they are both saltwater and freshwater
They contain saltwater and freshwater
The Persian Gulf is saltwater, not freshwater.
Saltwater is heavier because saltwater contains salt which adds to its overall weight. Freshwater does not have any dissolved salt so it is lighter then saltwater
freshwater