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. Biofilters are essential in Recirculating Aquaculture Systems (RAS) for water purification. While mechanical filters primarily remove solid wastes like uneaten fish feed, biofilters contribute to overall waste treatment by processing dissolved waste products resulting from the decomposition of feed and fish waste. Thus, Statement 1 is considered correct in the broader sense of waste processing. 2. The primary and critical function of biofilters in aquaculture is nitrification. This biological process involves bacteria converting highly toxic ammonia (from fish waste) into nitrite, and then into relatively non-toxic nitrate. Hence, Statement 2 is correct. 3. Biofilters are focused on the nitrogen cycle and do not increase phosphorus. Phosphorus in RAS mainly comes from fish feed, and managing its levels often involves removal techniques, not addition via biofilters. Hence, Statement 3 is incorrect. 4. Based on the analysis, statements 1 and 2 are correct, while statement 3 is incorrect. Therefore, only two of the statements are correct.