How can you tell a fish is fish?

This is a bit of a trick question! It plays on the idea that "fish" is a category, but it's not actually a single, clear-cut scientific classification.

Here's why:

* Fish are a diverse group: The term "fish" encompasses a huge range of aquatic creatures, from tiny krill to massive whales. Some fish are very different from others!

* Scientific classification: Biologists use a system of classification that goes beyond "fish." They group animals by shared characteristics like bone structure, body shape, and how they breathe. So, a goldfish, a shark, and a tuna are all "fish" in the general sense, but they belong to very different classifications within the animal kingdom.

How can you tell if something is a fish?

Here are some general characteristics that most fish share:

* Live in water: This is the most obvious clue.

* Gills for breathing: Fish use gills to extract oxygen from the water.

* Fins for movement: Most fish have fins that help them swim.

* Scales: Many fish have scales that cover their bodies.

* Cold-blooded: Fish are cold-blooded, meaning their body temperature changes with the environment.

So, while there's no single answer to how to tell if a fish is a fish, you can use these characteristics to help you identify fish from other aquatic animals.