What feature is cited as the most reliable, non-size-dependent identifier for young flathead catfish compared to young channel catfish?

Answer

The head shape, appearing noticeably broader and flatter

Even when small, the reliable feature remains the head shape; a young flathead's head will appear noticeably broader and flatter than a channel catfish of the same length.

What feature is cited as the most reliable, non-size-dependent identifier for young flathead catfish compared to young channel catfish?
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