Ahhh ... common names
plecostomus turned into pleco, sucker fish, janitor fish ...
just how in some fashion Astronotus Ocellatus became Oscar, Velvet Cichlid, Marble Ciclid ...
Not to be picky, but janitor fish gives a bad impression, or to me sells a misconception that they eat poo and shouldn't be cared for properly, at least I have found that to be the common attitude towards them by the uninformed public.
You must have good temperatures around there for that thing to grow so big and healthy

I would assume an unattended pond would grow its fair share of algae, and keep that big guy well fed