Once it gets to know you it will eat everything. Though some betta are finicky eaters and show betta in general have that rep.
A depressed or bored betta won't eat. We have several in QT
tanks right now as we clean and de-gravel their 10 gallons, and they are eating the bare anount to live(2 pellets as compared to their 8-9)
But I have not had any betta refuse food for more than 3-4 days before making exception. Bet they are flake eaters(kinda lke breaking a kid from eating chips all day).
And the fem trio even eat the algae pellets and zuchinni meant foir their otos
OMG!!EDIT! that is 3-4 days ..NOT 43! Darn dyslexia!