Gas bubble disease results from exposure to which gas?

• A. Oxygen
• B. Ammonia
• C. Nitrogen
• D. Hydrogen sulfide

Answer: (C)

Gas bubble disease happens when water becomes supersaturated with dissolved gases, especially nitrogen. Nitrogen is inert and not readily used by the fish, so when the pressure drops or the water is heavily aerated, dissolved nitrogen comes out of solution and forms bubbles inside tissues and in the bloodstream. Those bubbles disrupt circulation, damage organs, and produce symptoms like buoyancy problems and tissue injury. Oxygen, while essential for metabolism, doesn’t form these emboli under typical aquaculture conditions, and dissolved ammonia or hydrogen sulfide are toxic chemicals that harm fish through chemical irritation and toxicity, not by creating gas bubbles. Preventing gas bubble disease involves keeping water gas levels at equilibrium with the atmosphere and avoiding rapid pressure changes or conditions that drive degassing.