Which statement best describes dissolved oxygen in aquaculture systems?

Which statement best describes dissolved oxygen in aquaculture systems?

• A. It is the oxygen dissolved in water that supports aquatic life
• B. It is the oxygen bound to solids
• C. It is the oxygen gas released to the atmosphere
• D. It is not required by fish

Answer: (A)

Dissolved oxygen is the oxygen gas that has dissolved in the water and is directly available for fish to use in cellular respiration. In aquaculture, this is the essential form of oxygen that supports life, and its level is influenced by temperature, salinity, and how well the system exchanges gases with the air. Keeping DO at adequate mg/L or percent saturation is crucial because low DO stresses fish, slows growth, and can lead to mortality. The other ideas don’t provide usable oxygen for metabolism: oxygen bound to solids isn’t readily accessible to fish, oxygen gas released to the atmosphere leaves the water, and fish clearly need oxygen to survive.

Dissolved oxygen is the oxygen gas that has dissolved in the water and is directly available for fish to use in cellular respiration. In aquaculture, this is the essential form of oxygen that supports life, and its level is influenced by temperature, salinity, and how well the system exchanges gases with the air. Keeping DO at adequate mg/L or percent saturation is crucial because low DO stresses fish, slows growth, and can lead to mortality. The other ideas don’t provide usable oxygen for metabolism: oxygen bound to solids isn’t readily accessible to fish, oxygen gas released to the atmosphere leaves the water, and fish clearly need oxygen to survive.