Otocinclus, like any other fish species, do produce waste material. Still, considering their small size, the amount of waste they generate is relatively less compared to larger fish species. Keeping this in mind, a couple of Otos won’t drastically impact the overall bioload of your aquarium.
However, having a reliable filter mechanism in place, conducting regular waste checks and performing routine water changes is essential. Overlooking these aspects can accumulate toxins in the tank and create unhealthy and stressful conditions for your aquarium inhabitants.