In aquaculture water quality, which statements are true?

• A. Both statements are true
• B. Only TAN stands for total ammonia nitrogen
• C. Only DO stands for dissolved oxygen
• D. Neither statement is true

Answer: (A)

Two common water-quality terms in aquaculture are TAN and DO. TAN stands for total ammonia nitrogen, the combined amount of ammonia (NH3) and ammonium (NH4+) in water, reported as nitrogen; this form can be toxic to fish, especially at higher pH and temperature. DO stands for dissolved oxygen, the concentration of oxygen gas that is dissolved in water and available for aquatic organisms to breathe. Both statements are true: TAN indeed stands for total ammonia nitrogen, and DO indeed stands for dissolved oxygen. Being familiar with these terms helps you interpret water-quality data and assess the risk from ammonia toxicity and the adequacy of oxygen for respiration.