You'll be fine. Anything past 4-5 times recommended dose I might keep an eye on but I would guess you would still be okay as long as it wasn't a real small tank. When in doubt do a water change.
It depends on the type/brand of conditioner, and how much water is the Betta tank can hold.
I have Siamse Fighting Fish. and yes, you can! But I would suggest you read the pack because to much can kill you fish!
Use water from the tap, and then use Tap Water Conditioner. The bottle usually says how much is needed depending on how much new water you're using.
There will be no more fish in the world
Yes. Anything poured into the water of a fish can potentially kill it, whether it is toxic by itself or it just changes the temperature or something else... the water to fish, is like the air to us, and if someone loads up our air with smoke or pollution we can get sick, and if there is too much, we can die.
They can't swim underwater. As the density of the extremely salty water is so much greater, the fish would float on the surface of the water. As a result, the fish will die after some time. Hmmm.
Yes you can. Follow the directions on the container. They are provided there for you to use so that you don't kill/damage your fish. I personally hate adding any kind of chemical to my aquaria. I stand any replacement water I intend to put in with my fish overnight in buckets. This allows the added chlorine to evaporate off so there is no need to use chemicals to remove it. If your water supplier adds chloramine rather than chlorine then you will have to use the conditioner as directed.
It depends on the fish.
It's not recommended because it's usually too hard. Tap water with dechlorinator added to it is the best way to go.
Wneh changing water for a Betta it is always better to simply let the fresh water stand (in a bucket or other container) overnignt before using it. The chlorine will evaporate off naturally. Then you don't need to put chemicals in the water to remove the chlorine. If you do use one of the many different chlorine removing chemicals it is best to read and follow the instructions on the packaging.
Different water suppliers add different quantities and different types of chlorine and chloramine. The only water that fish should be put in should have all the chlorine removed by either letting the gas evaporate off or by adding some commercially available "water conditioner" according to directions.
more fish live in the sea water because how much sea water there is