You don't have to, but a small amount of salt for freshwater tanks acts as a soothing 'tonic' for Freshwater Fish. Follow instructions on the package.
There are both marine (salt water) and fresh water fish in the tropics.
I think the fish you are asking about is the Siamese Fighting fish AKA (Betta splendens). They are tropical fresh water fish.
All salt water, fresh water, and tropical fish are cold blooded.
No! marine fish are salt water fish and tropicals are fresh water fish, this cannot be changed.
salt water, in corral bits in a reef or something, its a tropical fish.
Saltwater fish require salt water, and fresh water fish need fresh water, you can't mix them, or the fish will die. You need to look at each individual fishes needs as to what temp they need their water to be. There are some saltwater fish that can survive in fresh water, but it is not healthy for them.
Yes, most freshwater fish were not made to live in saltwater and they can die in the ocean. This is caused by a great loss of weight, due to the water in the fish being pulled out by the salt, and eventually death. About 2% of freshwater fish change to a saltwater environment sometime in their life, but this change happens gradually and they would most likely die if put suddenly into a saltwater environment.
Fresh water
Most salt water fish will die if placed in fresh water.
Well it depends on the fish. If it is a fresh water fish then it lives in fresh water, salt water fish live in salt water.
These spectacular fish (Pseudanthias species) are tropical marine (salt water) fish.
Fresh water.