Monitoring nitrite levels in water helps prevent which condition?

• A. Gas bubble disease
• B. Brown blood disease
• C. Acidosis
• D. Anemia

Answer: (B)

Nitrite toxicity in fish water mainly causes methemoglobinemia, which is known as brown blood disease. When nitrite enters the bloodstream, it binds to hemoglobin and converts it to methemoglobin. Methemoglobin can’t carry oxygen effectively, so the blood’s ability to deliver oxygen to tissues drops, leading to tissue hypoxia and stress. That’s why monitoring and keeping nitrite levels low is essential; it prevents this specifically oxygen-transport–impairing condition.

Gas bubble disease comes from gas supersaturation in the water, not from nitrite. Acidosis relates to pH imbalances, and anemia is a broad term for low red blood cells and isn’t the direct outcome of nitrite poisoning. The nitrite issue you’re preventing here is the methemoglobinemia that gives brown coloration to the blood and compromises oxygen transport.