Which one of the following fishes does not belong to class osteichthyes ?

Options

A. Hippocampus
B. Labeo
C. Torpedo
D. Exocoetus

Answer

To determine which fish does not belong to the class Osteichthyes, we can follow these steps:

### Step-by-Step Solution:

1. **Understand the Classification of Fishes**:
- Fishes are primarily classified into two classes: Osteichthyes (bony fishes) and Chondrichthyes (cartilaginous fishes).
- Osteichthyes have a skeleton made of bone, while Chondrichthyes have a skeleton made of cartilage.

2. **Identify Characteristics of Osteichthyes**:
- Osteichthyes are characterized by features such as the presence of an operculum (gill cover) and often an air bladder.
- Examples include common fish like salmon, goldfish, and rohu (Labio).

3. **Identify Characteristics of Chondrichthyes**:
- Chondrichthyes have a skeleton made of cartilage, lack an operculum, and typically have a more flattened body shape.
- Examples include sharks, rays, and skates.

4. **Analyze the Given Options**:
- **Option 1: Hippocampus (Seahorse)** - This fish belongs to Osteichthyes.
- **Option 2: Labio (Rohu)** - This fish also belongs to Osteichthyes.
- **Option 3: Torpedo (Electric Ray)** - This fish belongs to Chondrichthyes, as it has a cartilaginous skeleton.
- **Option 4: Exocoetus (Flying Fish)** - This fish belongs to Osteichthyes.

5. **Conclusion**:
- The fish that does not belong to the class Osteichthyes is **Torpedo (Electric Ray)**.

### Final Answer:
The fish that does not belong to class Osteichthyes is **Torpedo**.

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