To be honest I have A)- never heard of betta raised on ants B)- have never fed my bettas ants or know anyone who does C)- have noticed on occasion that when an ant fell in the tank the bettas ignored it. 

 I also know for a fact, due to the bizillion ants currently squatting in my pool yard area, that the little buggers bite (and hurt!). Hard to believe such tiny creatures can cause such pain. Also you never know where ants have been (munching on a bacteria potent cadaver near by, contaminated by pesticides, etc etc...) So me, personally I would not feed them to my fish. So let's switch Mr. Betta to something a bit more healthy.

As always when switching foods, it is recommended to not feed the fish for about 5 to 7 days. THEN feed it the new food. By then it is hungry enough to eat rocks LOL. Worry not, bettas can stay for quite a long time without eating if necessary and will survive. Pick some really tasty food to lure him away from his bad ant habit (the kind that bettas have a weakness for) such as frozen brine shrimp or bloodworms). Avoid flakes (they will ignore them) and pellets. Remove any uneaten food so to not foul the water. I would try to offer the new food daily for about 7 days. If after 7 days it will still not eat it, then you might have to feed ants again for a while so to not starve your betta. You could then consider having your betta join a local AA group (Antaholic Anonymous) LOL. 

If anyone else has heard of bettas raised on an ant diet (or tried it for a long period of time) please email me the details. I am dying to hear them ;).

 PS: If you can't find his daily share, come to my house, we've got enough  #@&*! ants this summer to feed the entire betta nation LOL.