The last food for betta fish that I advice is "Artemia".
Artemia is brine shrimp that grown to be adult.
In the nature artemia live in the sea or salt water ,so we must clean the salt in it with tap water about 2-3 times before we give it to our betta fish.
Artemia is the most cleanly food for betta because it lives in salt.
Give too much of artemia to betta fish will cause them indigestion and betta fish will die soon with no way to solve this problem.