Hi Frank, Firstly I'd like to say I'm a big fan of your books and blog and still re-read the original print version of Newts and Salamanders from time to time so please don't think i'm trying to be a smart @ss, it's just that Corydoras catfish with their dorsal and pectoral spines can be quite a risk with species that will pray on fish like Pachytriton.
I know lots of people keep them with newts and they're fine, but I have seen Paddletails as well as Axolotls and aquatic frogs and toads killed or injured by getting them stuck in their throats.
Maybe they are ok with smaller species, but definitely not Paddletail newts.
Best regards, Ben.