Tail fins and dorsal fins,Spread, expand, as well as sail,When flying in full mass,They captivate like nightingales,Attempting to breed baby fry,Their actions may surprise,For how betta fish procreate,Differs from routine rise...
Sorry for your loss:( What happened though.Do you need help to figure out what wrong in case you want to buy another betta? He looks good on the picture though.
If he was sick not sure what he has you might need to disinfect the tank before you put there another betta.
Do you need help on betta care in case you want another one? Sorry not sure how long you had them....just want to help :)