Sorry i just read you want suggestions other than corys, you could try otos but they are harder to look after.
You still have the option to pick 6-8 Pangio kuhlii or Turboschistura arakanensis if you like them.
I'm not mistaken with the name. Here it is. The name is still being argued. Someone wanted to rename it as Turboschistura shanensis because they are found in Shanan river system and not the Arakan river system.Hi Lupin, I still need to keep something at the top layer, not just bottom dwellers. With 6 kuhlii i would exhaust the tank limit on fishes cause its only a 20 gal. I could not find any reference on fishbase about Turboschistura arakanensis. Did you misspell it ? Now that the recommendation is not to worry so much about snails, i am not going to keep any burrowers. My idea is to keep a mix of top and bottom dwellers, as i beleive giving good living space for each member reduces tension and diseases. Besides, the bottom dwellers would clean up the left overs at the bottom and help to some degree keep conditions clean in water.
By the way, i did not mean to rule out corys. Panda corys is good suggestion.