Well I got desperate with Alexander here a couple weeks ago as he was eating everything that hit the water, snail food, oto food,
betta food, peas, you name it. So I took an algae wafer and soaked it in some (a couple tablespoons) of dechlorinated water and let it go to powder. Then I got an eyedropper and took the liquid and put as much in the eyedropper as it would hold. Then I put my hand with the eyedropper as far into toward the bottom back corner of the tank as I could get and squirted the food out. It made a momentary mess in the water but the powdered food settled fast and all over the gravel in the back of the tank. The otos and snail can eat it that way and the naughty little Alexander cannot so that took care of that for the moment.
Since then I have now gotten sponge filters for all of my tanks and the sponge filter sits within a half inch of the back wall of the tank. I just drop the wafer back there and Alex won't go there so the Otos fit there fine and the food is Alex-free and safe. He still loves the snail food but the snail is usually right there to eat it so he doesn't fight with him much.
Good luck. I hadn't heard from you for a while and was afraid you had had a disaster of some sort. Glad to have you back.
Rose