Many fishes of freshwater can't live in sea water and vice-versa because of

Options

A. nutrient
B. osmotic problems
C. breathing problems
D. excretion problems

Answer

### Step-by-Step Solution:

1. **Understanding Osmosis**:
- Osmosis is the movement of water across a semi-permeable membrane from an area of lower solute concentration (hypotonic) to an area of higher solute concentration (hypertonic).

2. **Freshwater Fish in Seawater**:
- Freshwater fish are hypertonic compared to their environment when they are in freshwater. This means they have a higher concentration of salts in their bodies than the surrounding water.
- When placed in seawater, which has a higher salt concentration (hypertonic), water will move out of the fish's body into the seawater.
- This leads to dehydration and plasmolysis of the fish's cells, ultimately causing the fish to die.

3. **Seawater Fish in Freshwater**:
- Seawater fish are adapted to live in a hypertonic environment, meaning they have a higher salt concentration compared to freshwater.
- When these fish are placed in freshwater, which is hypotonic, water will move into the fish's body.
- This influx of water can cause the cells to swell and potentially burst (lysis), leading to the death of the fish.

4. **Conclusion**:
- The inability of freshwater fish to survive in seawater and vice versa is primarily due to osmotic problems. The differences in salt concentration between their bodies and the surrounding water lead to detrimental water movement that can cause dehydration or cell bursting.

### Final Answer:
Many fishes of freshwater can't live in seawater and vice versa because of osmotic problems.

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