Why are they so expensive?
they're extremely difficult to care for mouthbrooders that like low pH...
Only specialists should try to keep the fish. Requires painfully pure and very soft water(90% RO), with a strong current, filtration over active peat. Large tanks are also advised, the fish can swim extremely fast, and have been known to kill themselves by swimming against the tank glass. Tanks should be covered extremely well, as Betta macrostoma is an excellent jumper, and is susceptible to cold air. Lot's of hideouts, especially floating plants, and very frequent large waterchanges. An UV filter is strongly recommended.
they start at about $80.
What kind of Betta should I get?