With reference to the role of biofilters in Recirculating Aquaculture System, consider the following statements : 1. Biofilters provide waste treatment by removing uneaten fish feed. 2. Biofilters convert ammonia present in fish waste to nitrate. 3. Biofilters increase phosphorus as nutrient for fish in water. How many of the statements given above are correct?

1. A. Only one
2. B. Only two
3. C. All three
4. D. None

Answer: B

Explanation

Let’s evaluate the statements regarding biofilters in Recirculating Aquaculture Systems (RAS):
1. Statement 1 is correct. Biofilters are designed to remove solid waste, including uneaten fish feed and faeces, through mechanical filtration and biological degradation, thus improving water quality.
2. Statement 2 is correct. Biofilters house nitrifying bacteria that perform nitrification, a two-step process converting toxic ammonia (from fish waste) first to nitrite and then to much less toxic nitrate, which is crucial for fish health.
3. Statement 3 is incorrect. Biofilters aim to remove excess nutrients like phosphorus and nitrogen compounds from the water to prevent eutrophication and maintain a healthy aquatic environment, not increase them. Some specialized biofilters can remove phosphorus.
Therefore, only two statements are correct. This question tests knowledge of sustainable aquaculture practices and environmental engineering.