A large portion of my son's original stock of cherries came from Tundragirl. She also included a variety of food to get him started, and we have yet to go through it all. Based upon what she sent, here was her recommendation for approx 2 dozen cherries of various sizes:
Spirulina granules or shrimp pellets - either 2 shrimp pellets or a pinch of spirulina every other day. For size comparison, the pellets are about 1/8 - 1/4 inch long max, by about 1/16 inch in diameter.
Dehydrated spinich and squash - one or the other, once per week. These are dime or smaller size pieces.
Fish flake food - I do not recall the original recommendation, but we feed a pinch of this on the alternate days I do not do the spirulina or shrimp pellets.
FWIW - we also have 2 ottos in this 10 gal tank.
I can tell you that originally, we were feeding a bit more than I just described. Snails were beginning to exceed the population of most small countries, so we backed off a bit to what I just described. Still have snails, but nowhere near as many as we once had. Plenty of plants, but quite frankly, the tank does not look nearly as nice as yours smalltank!!!