I've been curious about this as well. I'm Thinking if they can easily inhale it, it's food.
They won't eat fish, no matter how small. Won't eat inverts either. Despite their large mouths they don't act like groupers do
I don't know about that. All of mine behave like sharks in a blood rush when it's feeding time, They snap everything tossed into the tank without much discrimination.
I'm sure they will go after free-swimming shrimp like Mysis (they surely go after dead ones) and small fish larvae. Also, in the tank with my largest banggai female all sexy shrimp have slowly disappeared.
The anemone shrimp with my other pair of banggais is doing fine but those shrimp are quite big and always hiding within the green star polyps.
Though I agree that they likely don't go after small fish unless they are starving. Still, I would be cautious with tiny fish.
I guess if it's a issue or question then one shouldn't get a cardinal. This is nature and most things that can eat something else, often do. The cardinals just hang out and hover in a corner so I'm not really sure what they even bring to a tank
I dumped a dozen or so small Brown shrimp in my tank and my Dottyback went after them like a Great White. My larger Pajama tried to eat one but couldn't get it in it's mouth.I've known plenty to eat shrimp, one would even eat the largest of cleaner shrimp.
The cardinals just hang out and hover in a corner so I'm not really sure what they even bring to a tank