yeah Hikari tropical algal wafers are a great food for mainly vegetarian catfish or as part of the diet for omnivores. My goldies do eat a few of them on a regular basis and willl have a good crack at a piece of corgette as well but I also feed them shrimp pellets, carnivore tablets, shrimp tails and the odd feed of blood worms and fish.
What do you feed your monster goldie on KP?
The main problem with keeping more vegetarian plecos with the carnivores is that they will all eat high protein foods, often in preference to algal wafers, and a high protein diet is not good for the digestive system of vegetarian plecos. So a mango pleco and a goldie may get on OK in the same tank but while a high protein diet may be great for your goldie, it may eventually kill your mango pleco. I lost my big royal (28 cm) a while a go due to its fondness for carnivore tablets so I now only keep my carnivorous plecos together.