You can either let the tank sit 'fallow' (empty of fish) for about eight weeks or you can remove and boil the gravel, replace all the water and replace or boil all of the filter media and decorations.
Robert Frost
i dont really know sorry
they will die
Not if you stand idle. Empty 1/3 of you tank every week and replace with fresh water. That should keep things leveled.
A water pump is needed to pump in fresh water.
No! marine fish are salt water fish and tropicals are fresh water fish, this cannot be changed.
A fish tank is any container in which fish, either salt water or fresh water, can live comfortably and happily in an environment that replicates their natural habitat.
You could.... but I wouldn't recommended because it's not 100% healthy for the fish.
It is not recommended to mix salt water fish and fresh water fish. It is required to separate the two and provide each with the proper tempered water.
Most pet stores that sell fish also sell fresh and salt water fish. Read up and learn about salt water tanks because they are different to take care of than a fresh water tank.
A tank is just a box made out of glass. You could put either salt water or fresh water into this box with the appropriate filter media. No, fresh water fish cannot survive in salt water, but it doesn't matter what kind of tank (box) they are put in. note: most fresh water fish like a little bit of salt in their water. It improves their gill function and gives them needed electrolytes. However, this is only a small amount (1 tablespoon per 5 us gallons), so don't overdo it.
scoop water from existing tank place fish in it and scrub tank wiith salt and rinse thouroghly put fresh water give about a day for water to be at the steady room temp. and out fish back in