General Notes:

The males are extremely territorial particularly with their own kind. Only one male can be kept per tank, other fish are ignored. Passing females will be displayed to and if ready to breed the pair will be compatible for a short time, if the female is not ready or is unwilling to breed she will be treated as an intruder and chased away. Siamese fighters are tropical fish, not only that but they live in shallow water which gets quite warm and as a species they live at the higher end of the tropical fish temperature range. They should not be kept in small un heated vessels which are subjected to rapid changes of temperature and may become to cold at times.
Betta splendens can breathe atmospheric oxygen, this enables them to live in water with a low oxygen level. It does not mean that they can survive in polluted water. Betta splendens cannot tolerate ammonia or nitrite better than any other fish, this means that they need a mature filter in their aquarium as does any other fish.
As can be seen in the video, Beta's are active inquisitive fish and so need some space to be able to behave naturally and swim.

Betta splendens needs the same care as all other fish,
THEY SHOULD NOT BE KEPT IN A TINY UNFILTERED, UNHEATED "VASE" with the false notion that these fish live in tiny polluted puddles.

Feeding

Wild Betta splendens feed on small worms, insects, insect larva, crustaceans and very small fish (fry). In captivity they will accept flake food, freeze dried food, suitably sized live or frozen food. They are quite unfussy and are bold feeders.

Sexing

Males are larger more brightly coloured and with longer fins. There are some short finned males but it is still relatively easy to tell the sexes apart.

Breeding

Males construct a nest made from bubbles and weeds, they entice a ripe female under the nest and then the male flips the female over on to her back and then arches his body over hers, The eggs are then released and fertilised and then slowly fall to the floor. Before they reach the floor the male collects them in his mouth and places them in the nest. This process is repeated several times until all the eggs have been laid. The male then becomes highly territorial once again and chases his mate away. The male alone protects the brood.

It is often asked if it possible to keep Betta splendens in a community tank. Yes it is, provided the tank mates are carefully chosen. Any fish likely to nip fins are obviously out of the question, so are other fish with similar habits i.e other bubble nest builders. But with small peaceful fish which are to big to be eaten whole are generally fine especially in a well planted aquarium. Contrary to popular advice it is even possible to house a pair in a large well planted aquarium, I have done this personally and the pair would breed on a regular basis in the community tank. The trick is to have sufficient planting and a large enough space for the two to be hidden from each other and to escape each other. This obviously can't happen in a small bare tank, in such a situation the female would in all probability be killed.

Wild status

The wild population of Betta splendens has not been evaluated and so is unknown at this time.