Controlling Ammonia and Toxic Gases to Enhance Water Quality for Healthier Fish and Prawns in Aquaculture

AMMONIL-SP 1X500GM TIN Ammonia and toxic gas controller

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Aquaculture faces a constant challenge: maintaining water quality that supports the health and growth of fish and prawns. One of the biggest threats to aquatic life in farming systems is the buildup of ammonia and other toxic gases. These substances can quickly degrade water quality, stress aquatic animals, and reduce productivity. Understanding how to control these harmful compounds is essential for any aquaculture operation aiming to improve survival rates, growth performance, and overall health of cultured species.

Why Ammonia and Toxic Gases Are a Problem in Aquaculture

Ammonia is a natural byproduct of fish and prawn metabolism, as well as the decomposition of uneaten feed and organic waste. In water, ammonia exists in two forms: ionized (NH4+) and un-ionized (NH3). The un-ionized form is highly toxic to aquatic animals even at low concentrations. Elevated ammonia levels can cause gill damage, reduce oxygen transport, and impair immune function.

Other toxic gases such as hydrogen sulfide (H2S) and nitrite also accumulate in poorly managed systems. Hydrogen sulfide forms in oxygen-depleted sediments and is lethal to aquatic life. Nitrite interferes with oxygen transport in blood, causing a condition known as "brown blood disease."

When these toxic substances build up, fish and prawns become stressed, more susceptible to disease, and may experience slower growth or death. Therefore, controlling ammonia and toxic gases is critical for maintaining a healthy aquaculture environment.

Methods to Control Ammonia and Toxic Gases

1. Proper Feeding Management

Overfeeding is a common cause of ammonia buildup. Uneaten feed decomposes and releases ammonia into the water. Feeding fish and prawns the right amount, at the right times, reduces waste and ammonia production. Using high-quality, easily digestible feed also minimizes waste.

2. Regular Water Exchange and Aeration

Replacing a portion of pond or tank water regularly dilutes ammonia and other toxins. Aeration increases oxygen levels, which supports beneficial bacteria that convert ammonia into less harmful substances. Proper aeration also prevents the formation of hydrogen sulfide by keeping sediments oxygenated.

3. Biological Filtration

Biofilters use beneficial bacteria to convert toxic ammonia into nitrate through a process called nitrification. These bacteria thrive in filter media with a large surface area. Installing biofilters in recirculating aquaculture systems (RAS) or pond setups helps maintain low ammonia levels continuously.

4. Use of Aquatic Plants

Certain aquatic plants absorb ammonia and nitrates directly from the water. Incorporating plants like duckweed or water hyacinth in or near culture ponds can improve water quality naturally. Plants also provide shade and habitat, which benefits fish and prawn welfare.

5. Sediment Management

Removing organic sludge from pond bottoms prevents anaerobic conditions that produce hydrogen sulfide. Regular sediment removal or turning helps maintain aerobic conditions, reducing toxic gas formation.

How Improved Water Quality Benefits Fish and Prawn Health

Controlling ammonia and toxic gases leads to clearer, oxygen-rich water that supports healthy aquatic life. Fish and prawns in clean water exhibit:

• Better growth rates due to less stress and improved metabolism

• Stronger immune systems that resist infections

• Higher survival rates during critical life stages

• Improved feed conversion efficiency, reducing production costs

  
  

For example, studies have shown that shrimp grown in well-aerated ponds with biofiltration systems have significantly lower mortality and faster growth compared to those in unmanaged ponds. Similarly, tilapia exposed to low ammonia levels show better feed intake and less disease.

Practical Tips for Aquaculture Farmers

• Monitor water quality parameters daily, especially ammonia, nitrite, and dissolved oxygen.

• Avoid overstocking ponds or tanks to reduce waste accumulation.

• Use aerators or paddlewheels to maintain oxygen levels above 5 mg/L.

• Install biofilters in recirculating systems or consider integrated multi-trophic aquaculture with plants.

• Schedule regular pond bottom cleaning to prevent sludge buildup.

• Train staff on proper feeding techniques and water quality management.

  
  

Final Thoughts on Maintaining Healthy Aquaculture Systems