I've noticed the same thing recently with sinking feed.
Had some high quality meat-first kitty treats that the cats refused to eat. They're Standard American Dieters, prefer heavily salted, over-processed GMO corn flake treats. Thought "What the heck. Let's see what the fish think." They LOVED the stuff. Were crashing into each other to get at it. No time for it to sink very far once the gang showed up, but I agree that they seem to prefer "catching" the food as it drifts downward.
Real interesting creatures, aren't they? I could watch 'em half the day.
