otos with plastic plants? the poor things. Mine love to eat algae off of the live plants and they sleep on the leaves, wake up to munch, then go back to sleep. they eat a lot, but they're very lazy. :)
Otos do not eat 'old' algae. If the algae has been there a while and it's old, the otos will starve rather than touch it. As well, otos only eat some types of algae...
I noticed on my tank that one wall was covered in algae that was turning all brown - and the otos completely ignored that glass - wouldn't even touch it. Last night, I finally took the algae scraper and got it all off.
The otos just seem to like cleaning my plants mostly, and then swimming over to the slice of zuccini ... They're all very fat ... such gluttons for veggies. I think my otos may be vegans. :)