Indoor Application of a Coupled Flocponics System with Caipira Lettuce (Lactuca Sativa) Affects the Growth Performance and Water Characteristics for Far Eastern Catfish (Silurus Asotus) and Tropical Eel (Anguilla Bicolor)

Abstract

In this study, we sought to improve the productivity of Far Eastern catfish (Silurus asotus) and tropical eel (Anguilla bicolor),  which are high-value fish species in South Korea, as well as that of associated crops by applying biofloc technology  (BFT)-based aquaponics systems. Three systems were used: Flow-through system (FTS), BFT, and BFT aquaponics system (BAPs).  Caipira lettuce (Lactuca sativa) was utilized and hydroponics (HP) was implemented to compare crop productivity.  After 42 days of treatment, the BAPs and BFT systems improved fish productivity, with weight gain rates of 134.47 ± 1.80%  in BAPs-cat, 130.38 ± 0.95% in BFT and 114.21 ± 6.62% in FTS for S. asotus, and 70.61 ± 3.26% in BAPs-eel, 62.37 ± 7.04% in BFT,  47.83 ± 1.09% in FTS for A. bicolor. During the experiment, total ammonia nitrogen and NO2--N concentrations were stable  in all plots. In the case of NO3--N, BFT showed an increasing tendency while both BAPs showed a decreasing compared with  that of the BFT. BAPs-cat (total weight: 224.1 ± 6.37 g) and HP (220.3 ± 7.17 g) resulted in similar growth.  However, in BAPs-eel was 187.7 ± 3.46 g due to root degradation. Water content analysis showed  that BAPs-cat and BAPs-eel contained sufficient K, Ca, P, and S, which are important for crop growth. Overall,  the effect of BAPs on fish growth was higher than that of FTS. This study reveals that integrating BFT  with aquaponics improves productivity for high-value fish and associated crops while maintaining stable water quality.  This method offers sustainable, efficient production, reduces environmental impact, and provides insights for future research  in sustainable aquaculture practices.

Keywords: Far Eastern Catfish, tropical Eel, Biofloc, Aquaponics, Hydroponics