I am a little late to this thread whoops!
If you house Oto's with your Betta, do NOT feed them sinking tablets. Instead, use fresh veg on clips, which the Betta will stay away from.
It is not unheard of for a Betta to gorge on an Algae tablet, a food they were never meant to eat, and die. I don't mean to sound alarmist, but I have seen this first hand. Most Betta do not know when to stop eating, that coupled with the vegetable matter which is hell on their digestive tract, it could spell the end for a Betta.
2 10 gallon tanks, 1 20 gallon tank, 1 Fluval Edge, 1 29 gallon tank, and one backyard pond.