The Bare Bones, Must Haves...
1. A Betta
2. A container or tank
3. Water Conditioner
Lots of options, but those are the basic "Must Haves"
Bettas are commonly thought to have origonated in Thailand, formerly known as Siam. Hence their other name, the Siamese Fighting Fish. For over a century they were kept by many people, and used in as a fighting fish for wagers.
The more modern version of these pet fish is a result of many decades of selective and cross breeding. All the wonderful shapes and colors now available is a result of this process. They are now classified as Betta Splendens, and look very little like their wild cousins.
Although pet Bettas do not truly exist in the wild, they are close enough that duplicating the wild habitat is a good start.
Wild bettas generally live in rice fields or swamps, in congested overgrown areas, in warm water. The water does not have much movement, so they have developed the ability to gulp bubbles of air and push it through their gills. This is why they can live in small amounts of water with no pumps. They live solitary, not in schools, and tend to stay hidden near a plant or other suitable hiding place.
Although they probably could and do survive this way in the wild, they are NOT commonly found in small puddles. Small puddles don't tend to stay around very long, so it is unlikely any fish can live in them long term.
Care in Captivity
Please keep in mind there are many, many ways to keep your pet We encourage you to research and learn more all the time.
For many decades bettas have been kept in small bowls, even cups. Although they can obviously survive this way, it's kind of boring. So we generally recommend an aquarium or larger bowl, somewhere about 2 to 5 gallons. Smaller or bigger can work as well, but this range is a good starting point.
Bettas require clean, warm water to thrive. You do not necessarily have to have a filter, but it will make your cleaning chores easier. A slow flowing basic filter is fine. If you don't purchase a filter, you ARE the filter, and keeping water clean falls to you. Generally a bowl without a filter needs cleaned weekly.
An aquarium with a filter monthly.
A low wattage aquarium heater will keep the tank warm, close to 80 degrees. Or you can place it in a warm area of your home. Windows are tricky, as temperature swing up and down which is not always a good idea. Plus sunlight grows algae. That makes it hard to see your betta.
Always condition new water with a chlorine / chloramine remover. It is never harmful no matter where your water comes from. And without it. your fish is likely to die within hours as chlorine burns the gills. Feed your betta once or twice a day, in small amounts. They tend to eat their fill quickly, and don't care for left overs. In a short time, left over food begins to spoil and make a mess. It makes the aquarium smell, and pollutes the water they breathe. And means you have to clean more often.
Remember that in the wild they live in overgrown areas around plants, so give them some decor to feel safe. Live plants are excellent, though artificial ones can work. You can go for a natural setup, or make it a theme tank. They generally won't care too much, as long as the decor is safe for them.