Tan is the byproduct of __ metabolism

• A. Oxygen
• B. Protein
• C. Fatty acids
• D. Carbohydrates

Answer: (B)

When proteins are broken down in the body, nitrogen is removed from amino acids and released as ammonia. In aquaculture, that ammonia shows up in the water as total ammonia nitrogen (TAN). So TAN is effectively the byproduct we see from protein metabolism, since proteins are the source of the nitrogen that becomes ammonia. In contrast, metabolism of fats and carbohydrates mainly yields energy as CO2 and H2O and does not produce nitrogenous waste in the same way. Oxygen isn’t a byproduct of metabolism either; it’s used during respiration. In practice, monitoring TAN is essential because ammonia can be toxic to fish, and it’s managed by feeding appropriately, biofiltration that converts ammonia to nitrite and nitrate, and regular water changes.