Whale is the largest known fish.

Answer

**Step-by-Step Solution:**

1. **Identify the Subject**: The question states that "Whale is the largest known fish." We need to clarify that this statement specifically refers to the whale shark, not all whales.

2. **Scientific Classification**: The whale shark is scientifically named *Rhincodon typus*. It is important to note that while the term "whale" is used, the whale shark is indeed a fish, classified under the category of cartilaginous fish (Chondrichthyes).

3. **Size Comparison**: The whale shark is recognized as the largest fish species, capable of reaching lengths of over 40 feet (approximately 12 meters). This size surpasses that of all other known fish species.

4. **Breathing Mechanism**: Unlike typical bony fish, whale sharks have a unique adaptation that allows them to access more oxygen. They can extract oxygen from water more efficiently, which supports their large size. They can access 20 to 50 times more oxygen than regular fish, which is a significant factor in their growth and size.

5. **Conclusion**: Based on the above points, we can justify the statement that the whale shark is indeed the largest known fish. Therefore, the assertion that "whale is the largest known fish" is correct when referring specifically to the whale shark.

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