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Effects of Fish Stocking Density on Water Quality, Growth Performance of Tilapia and Yield of Butterhead Lettuce Grown in Decoupled Recirculation Aquaponic Systems

Al Tawaha Abdel Razzaq, Wahab Puteri Edaroyati Megat, Jaafar Hawa Binti, Zuan Ali Tan Kee, Hassan Mohd Zafri

Journal of Ecological Engineering

2021

Vol. 22, nr 1

8--19

This study was conducted over a period of 52 days to determine the effects of fish stocking density on the water quality, growth performance of tilapia and yield of butterhead lettuce cultivated in decoupled recirculation aquaponic systems (DRAPS). In this study, three respective tilapia stocking densities (treatments) of 8 kg•m-3, 10 kg•m-3, and 12 kg•m-3 were used to evaluate the butterhead lettuce in the DRAPS, which consist of two independent loops. All treatments were done in triplicates. The results showed with increased stocking density, the electrical conductivity, total dissolved substances and salinity increased and dissolved oxygen decline. The results showed that the highest stocking density produced the highest nutrients accumulation of ammonia-nitrogen (NH3-N), ammonium (NH4), nitrite-nitrogen (NO2-N) and nitrate-nitrogen (NO3-N) and potassium (K) except for phosphorus (P). Nevertheless, based on the conversion of fish feed to NO3-N and P per kilogram of feeds, the lowest stocking density provided the highest concentration of NO3-N and P. It was documented that DRAPS relied solely on the fish waste produced an insufficient concentration of N, P, K and iron. The average survival rate of tilapia in all treatments was above 94% and was not a significant difference among the treatments.

Yield and Nutrients Leaf Content of Butterhead Lettuce (Lactuca Sativa) in Response to Fish Nutrient Solution in a Small Scale of Aquaponic Systems

Al Tawaha Abdel Razzaq, Megat Wahab Puteri Edaroyati, Binti Jaafar Hawa, Kee Zuan Ali Tan, Hassan Mohd Zafri, Al-Tawaha Abdel Rahman M.

Ecological Engineering & Environmental Technology

2021

Vol. 22, iss. 6

85--94

This study was conducted over 52 days to evaluate the potential of using the nutrient solution produced from different fish stocking densities on the yield and nutrients leaf content of lettuce cultivated in decoupled recirculation aquaponic systems (DRAPS). In this study, three stocking densities of tilapia were used 8, 10 and 12 kg m-3, respectively. The result showed the highest total yield 448 g m-2 was obtained at a low stocking density. Also, it has been showing that with an increased fish stocking density, the leaf nutrient content of butterhead lettuce for potassium, calcium, magnesium, sodium, iron and copper was increased. While for the nitrogen, phosphorus and manganese, the higher leaf content was obtained at lower stocking density. Considering the lettuce yield, leaf nutrient contents and nitrogen dynamics, the stocking density of 8 kg m-3 could be suggested as the ideal stocking density for DRAPS.