Biological filters are systems that use living organisms to remove contaminants from water or air. They often rely on bacteria, plants, or other microorganisms to break down harmful substances, converting them into less harmful forms. This process is essential in maintaining clean environments in aquariums, wastewater treatment plants, and natural ecosystems. In aquaculture, biological filters help maintain water quality by processing waste products from fish and other aquatic life. By promoting the growth of beneficial bacteria, these filters can effectively reduce ammonia and nitrite levels, ensuring a healthier habitat for fish and other aquatic organisms.