Any fish needs a variety of foods in order to maintain health, just as humans do. One food source just isn't going to provide what an animal needs. So I would vary the menu quite a bit.
Not to mention that you'd spend a fortune in Bloodworms to feed these fish! Without specifying what type of catfish, you've got at least sixteen feet of fish there, when it's all said and done. The catfish will just add to that number! You really are going to want to get them on pellets and cheaper food items, like fish filets you can buy in bulk, etc. You don't say how large they are now, but they're going to start eating Bloodworms like nobody's business, and Bloodworms are so small it'll take a bunch!
I'm not really familiar with the Knives, but I'm sure someone will wander in who can help you with their needs as far as feeding.
The Oscars should take to a Cichlid Staple pellet, like Hikari (do you have that there) Cichlid Staple or Cichlid Gold, with no problem. They'll also like veggies, such as peas, and fish filet/shrimp, etc.
Catfish is a broad term (could be several different types of Catfish), so we'll need some more specific info there in order to determine what you could feed. If this is the RTC/TSN (Pimelodid) catfish, then you're looking at fish filets, earthworms, Sinking Pellets (Hikari Massivore, Algae Wafers), shrimp, etc. For the Suckermouth Catfishes (Plecos), sinking pellets, Zucchini, Sweet Potato, etc. And, there are other types, as well. So just let us know what type you have, and we can help you figure out what to feed it.
As I said, just feed a variety, and if you do feed these dry pelleted foods, make sure that you're also feeding a wet-frozen or wet food, like the fish filets or vegetables.
Lastly, I must say that this must be a truly massive tank! You've got to show pics!
