B. prima is a rather plain-looking mouthbrooding Betta.
They can reach the size of about 5 cm.
The known distribution area to date is in the central plain of Thailand eastward, to somewhere in Cambodia. They are found foraging among the dense vegetation along the banks of the stream where the pH is neutral with gravel bed.
They are easily bred and will shown their best colour - iridescent blue-green shine - in a dark tank with dense vegetation.
Like all other Pla Kat, B. prima will enjoy live food such as Mosquito larvae, Daphnia, Bloodworm, Tubifex worm and Brine Shrimp. If you use Brine Shrimp, make sure to rinse them well in freshwater as the salt is very bad for the kidneys of freshwater fish.
best i could find from
http://www.fbas.co.uk/Newbettas.html