Most any aggressive larger fish will kill it.
yes, depending on its size and the size of the other fish.
From a petstore like (pet-co) or your Wal-mart
no, they are basically giant gold fish.FRESH WATER FISH. although you can add about one tablespoon aquarium salt to 10 gallons of water.It helps the fish to not be stressed,they will thrive.also use...
yes as long the fish mate is bigger than the koi mouth.