Changes in Pond Bottom Conditions Throughout Aquaculture Stages

Changes in Pond Bottom Conditions Throughout Aquaculture Stages

It is well-known that water quality control is crucial in aquaculture, and water quality is closely related to the condition of the pond bottom. Good pond bottom quality facilitates the development of aquaculture. This article will focus on the changes in pond bottom conditions at various stages of the aquaculture process and the corresponding measures.

During the aquaculture process, the pond bottom typically undergoes four changes: organicization, reduction, toxicification, and acidification.

Early Stage of Aquaculture—Organicization

In the early stages of aquaculture, as feeding increases, the accumulation of debris, residual feed, and feces on the pond bottom leads to a gradual build-up of organic matter, a process known as organicization. At this stage, oxygen levels are relatively sufficient. The main goal is to decompose the sludge and feces on the pond bottom, transforming them into inorganic salts and nutrients to promote algae growth and increase the dissolved oxygen in the water. Microbial strains can be used to help decompose sludge and feces.

Mid Stage of Aquaculture—Reduction

As aquaculture progresses, particularly during the peak feeding period of aquatic animals, the amount of feed continues to increase, resulting in a gradual accumulation of organic matter in the pond that exceeds the water body's self-purification capacity. A large amount of organic waste undergoes anaerobic decomposition at the bottom, leading to black and foul-smelling water, and entering the reduction phase where the water gradually becomes oxygen-depleted. For example, sulfate transforms into hydrogen sulfide, and ammonia nitrogen converts into nitrite. The result of reduction is significant oxygen depletion at the pond bottom, leading to pond hypoxia. At this stage, it is recommended to use oxidizing agents for bottom modification, such as potassium monopersulfate compound and sodium percarbonate. These oxidizing agents can oxidize pond bottom sludge, reduce oxygen consumption, and improve oxidation potential to remove black and odor issues.

Late Mid Stage of Aquaculture—Toxicification

In the late mid stage, the pond generates a significant amount of toxic substances, including hydrogen sulfide, ammonia nitrogen, nitrite, and methane. Especially hydrogen sulfide and nitrite can cause respiratory difficulties or even suffocation in fish, shrimp, and crabs. Therefore, when nitrite and ammonia nitrogen levels are elevated, it is advisable to use detoxifying agents to neutralize these toxic substances.

Late Stage of Aquaculture—Acidification

By the late stage of aquaculture, the pond bottom becomes acidic due to the anaerobic fermentation of large amounts of organic matter, resulting in a lowered pH and increased toxicity of hydrogen sulfide. At this stage, lime can be applied to the areas with the most accumulated sludge to neutralize the acidity of the pond bottom, raise the pH, and reduce the toxicity of hydrogen sulfide.