What effect does low dissolved oxygen have on fish health?

Low dissolved oxygen levels negatively impact fish health primarily by causing stress and potentially leading to suffocation. Fish rely on dissolved oxygen in the water to breath through their gills. When oxygen levels drop, fish may struggle to meet their metabolic demands, which can result in a variety of physiological stresses.

Exposure to low dissolved oxygen can lead to reduced energy levels, decreased appetite, impaired immune function, and increased vulnerability to disease. In severe cases, insufficient oxygen can result in hypoxia, where fish are unable to extract enough oxygen to survive, which ultimately can lead to death.

Therefore, the correct answer reflects the critical importance of adequate dissolved oxygen levels for maintaining fish health and overall well-being.