Which of the following fish is introduced in pond to control or eliminate the vector responsible for the transmission of malaria and filariasis?

Options

A. Exocoetus
B. Pristis
C. Scoliodon
D. Gambusia

Explanation

To solve the question regarding which fish is introduced in ponds to control or eliminate the vector responsible for the transmission of malaria and filariasis, we can follow these steps:

### Step-by-Step Solution:

1. **Identify the Diseases and Their Vectors**:
- Malaria is caused by the protozoan parasite *Plasmodium* and is transmitted by the bite of the female *Anopheles* mosquito.
- Filariasis is caused by the parasite *Wuchereria* and is transmitted by the bite of the infected female *Culex* mosquito.

2. **Understand the Role of Fish in Vector Control**:
- To control the populations of mosquitoes that transmit these diseases, certain fish species can be introduced into ponds. These fish feed on mosquito larvae, thereby reducing the number of adult mosquitoes that can transmit the diseases.

3. **Identify the Fish Species**:
- Among the options provided, we need to identify which fish is known for its larvivorous (larvae-eating) properties. The options given are:
1. Exocetus
2. Pristis
3. Scoliodon
4. Gambusia

4. **Select the Correct Fish**:
- The fish that is specifically known for feeding on mosquito larvae is *Gambusia*. This fish is commonly introduced into water bodies to help control mosquito populations.

5. **Conclude the Answer**:
- Therefore, the correct answer to the question is option 4: **Gambusia**.

### Final Answer:
The fish introduced in ponds to control or eliminate the vector responsible for the transmission of malaria and filariasis is **Gambusia**.