yes it is diatoms, nice i will continue to grow it so that there will be food for the ottos.You sure it's not diatoms? If so, yes they do eat that.
They can survive on the biofilm on all surfaces, plants, equipment and hardscape in the aquarium. I do not believe they need algae grown for themyes it is diatoms, nice i will continue to grow it so that there will be food for the ottos.