Well its good that they haven't gotten sick
Means you take good care of them!
The reason I suggest a snail instead of the ottos is because the ottos only eat algae...algae tablets etc...they like veggies, so they're a little bit more of a challenge to feed if you dont have algae for them to snack on. Snails are easy...they'll eat whatever they can suck up, bits of food, waste, algae etc
Or if you have pygmy cories at a lfs they would be a fun addition to the tank too.