When you say that "Corys shouldn't be just left to scavenge" I think I understand what you mean - please correct me if I am wrong - but you seem to be saying that they shouldn't be treated as "second class citizens." They shouldn't be expected to scour trash bins for their sustenance. My point of view is that that is exactly what millions of years of selective breeding has placed them in an ideal position to do. That downturned mouth and those exquisitely sensitive barbels make sure that they can find and selectively consume precisely those food stuffs that they require without any special help from us. Only if you view their food searches as indicating that they are relegated to licking the floor

does their lifestyle appear to place them in a position where they are being poorly treated. On the contrary, they are very well adapted and specialized to fit a niche where they are quite successful.
The 10 Corys in my 410 are constantly grazing - that's what they do. I don't claim to know entirely what their diet consists of but, with flake food, frozen shrimp and frozen blood worms fed during the lighted period in the aquarium, they are thriving. They have a lot of competition but some of the food always makes it to the bottom (even with a 30 inch depth!) and their bodies are consistently a picture of good health. They move well and rarely hide, even though they have many opportunities. To me scavenging isn't their "job", it's their evolutionary niche! I am simply enabling their genetic disposition to fill that niche. And I thank them for helping keep my aquarium clean. But my emphasis is on the fact that it is a two way street - a win-win situation. They are very good at what they do and would no doubt consider it insulting for me to think that I need to hold their hand.
Of the approximately 80 fish in this aquarium 37 are "scavengers." Some of my favorite fish! I rarely see all four of my striped rafaels or all five of my Synodontis at one time. They choose to be active at night. And from the fact that they have been in the aquarium for more than 6 months and are growing quite nicely, I'm certain their nutritional needs are being met. Again no special feeding. The 4 pictus have staked out territories within 2 square feet of space where they hassle each other constantly in spite of the fact that they have 25 square feet of space to choose from! They are more comfortable in close proximity apparently. The entire aquarium is heavily planted and has large pieces of driftwood and rocks and so offers many other hiding and territorial possibilities. I mention this pictus behavior because it illustrates my effort to simply provide an environment which is conducive to good health and then allow the fish to make their own choices.
My choice, after more than 40 years in this hobby, is to constantly improve my ability to observe and evaluate. My husbandry practices have allowed me to breed many different species of birds, mammals, fish and reptiles, as well as put food in my mouth. I had 2 spotted rafaels for more than 15 years (lost them during a move). All of my current population of parrots (5) and snakes (4) are over 20 years old. I become very disappointed with myself if I find that I have failed in my effort to do the best by my critters. And, after all that has been said, I still feel that I am treating my Corydoras well. I am not saying that you aren't, just that special foods and feeding practices are extraneous. My rottweilers would love it if I grilled them steak every night for dinner but they certainly don't need it!
I thoroughly enjoy a good discussion, especially with someone with whom I have a disagreement, so if you're interested, Cory Lover, please continue this thread. Spirited, rational arguments, without malice, are some of the best learning experiences available and an active mind is a healthy mind.
With the best of intentions,
Beasts