Fish which can be used in biological control of mosquitoes/Larvicidal fish is

Options

A. eel
B. carp
C. cat fish
D. Gambusia

Explanation

### Step-by-Step Solution:

1. **Understanding the Question**: The question asks for a specific type of fish that is used in biological control to manage mosquito populations, specifically referring to larvicidal fish.

2. **Identifying the Fish**: The fish that is commonly known for its ability to feed on mosquito larvae is the Gambusia fish. Its scientific name is Gambusia affinis.

3. **Function of Gambusia**: Gambusia fish are effective in controlling mosquito populations because they consume mosquito larvae. This makes them beneficial in areas where mosquitoes breed, such as ponds and lakes.

4. **Integrated Pest Management (IPM)**: The use of Gambusia fish is part of Integrated Pest Management (IPM), which is a strategy that combines different management approaches to control pests in an environmentally friendly way.

5. **Eliminating Incorrect Options**:
- Option 1: Eel - Incorrect, as eels do not primarily feed on mosquito larvae.
- Option 2: Calf - Incorrect, as calves are mammals and do not interact with mosquito larvae.
- Option 3: Catfish - Incorrect, as catfish do not primarily target mosquito larvae.
- Option 4: Gambusia - Correct, as it is known for its larvicidal properties.

6. **Conclusion**: The correct answer to the question is Gambusia, specifically Gambusia affinis, which is used in biological control of mosquitoes.

### Final Answer:
The fish which can be used in biological control of mosquitoes (larvicidal fish) is **Gambusia** (Gambusia affinis).

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