Kidneys of fishes do not play role in the elimination of

Options

A. Water
B. Ammonia
C. Homeostasis
D. Osmoregulation

Answer

**Step-by-Step Solution:**

1. **Understanding the Role of Kidneys in Fishes:**
- In fishes, the kidneys primarily function to regulate the balance of fluids and electrolytes in their bodies. They help in the excretion of waste products but have a limited role in certain types of waste elimination.

2. **Identifying the Waste Products:**
- The main waste product that needs to be eliminated from the body of fishes is ammonia, which is a byproduct of protein metabolism.

3. **Excretion of Ammonia:**
- Ammonia is highly soluble in water and is toxic at high concentrations. Fishes excrete ammonia directly into the surrounding water primarily through diffusion across their gill surfaces and body surfaces. This process does not significantly involve the kidneys.

4. **Evaluating Other Options:**
- The question provides options that include ammonia, homeostasis, and osmoregulation.
- Homeostasis refers to the maintenance of a stable internal environment, which the kidneys do help regulate in fishes.
- Osmoregulation is the process of maintaining water and salt balance, which is also a function of the kidneys in fishes.

5. **Conclusion:**
- Therefore, the kidneys of fishes do not play a significant role in the elimination of ammonia, as it is excreted directly through the gills and body surfaces. The correct answer is option 2: ammonia.

**Final Answer:**
The kidneys of fishes do not play a role in the elimination of ammonia.

---