* Fish are typically longer than they are wide. Most fish have a streamlined body shape for efficient swimming, meaning they are much longer than they are wide.
* The largest fish are often very long. Some of the largest fish, like the whale shark or the giant ocean sunfish, can grow to be very long, but they don't get that wide.
Possible Misunderstandings:
* You might be thinking of the *length* of the fish. It's more common for fish to measure 30 inches in length, not width.
* You might be thinking of a specific type of fish. There may be a specific species of fish that reaches 30 inches in some measurement, but it's unlikely to be "wide."
To help me understand your question better, could you please clarify:
* What kind of fish are you thinking of?
* Are you talking about the width, length, or another measurement?
* Is there a specific species you are curious about?