Effect of Dietary Monobasic Potassium Phosphate Levels on Water Quality and the Growth of Far Eastern Catfish Silurus asotus and Four Leafy Vegetables in a Hybrid Biofloc Technology Aquaponic System

摘要

This study investigated the effects of dietary monobasic potassium phosphate (MKP) on the growth of the far eastern catfish Silurus asotus and four leafy vegetables in a hybrid biofloc technology aquaponic system. To an experimental diet containing 45% protein and 7% lipid, 1, 2, 3 or 4% MKP was added and was designated as MKP1, MKP2, MKP3, and MKP4, respectively. The optimum MKP levels were determined for the growth of fish and four leafy vegetables over 10 weeks. After the 10-week feeding trial, weight gain, feed efficiency, specific growth rate and protein efficiency ratio were higher in the fish groups fed MKP2 and MKP3 than in the other groups (PO.05). The growth of the four leafy vegetables was also higher in the fish groups fed MKP2 and MKP3.Water quality [dissolved oxygen, pH, water temperature, electrical conductivity, turbidity, total ammonia nitrogen (TAN), NO_2-N, NO_3-N and PO_4-P] was measured six times a week using a portable water quality meter and reagent measurements. The TAN (4.58-20.40 mg/L), NO_3-N (24.12-52.40 mg/L) and PO_4-P (20.38-48.48 mg/L) levels increased with time, while the NO_2-N level remained below 0.1 mg/L throughout the study.