Aquamimicry feeding system improved growth, physiological status, muscle and intestine histomorphology, and flesh quality of keeled mullet, Liza carinata

Abstract

The aquamimicry feeding system (AMFS) is one of the modern aquaculture systems that aim to reduce feed costs and water exchange rates to improve the sustainability of aquaculture projects. In AMFS, the aquatic environment is simulated to produce natural food by adding probiotics to carbon sources. Therefore, a 108-day field study was conducted to evaluate the efficiency of AMFS as a solo feed or in combination with a commercial diet for the rearing of keeled mullet, Liza carinata. The L. carinata fingerlings with an initial body weight of 30.0 ± 3.25 g were randomly distributed into three experimental treatments in triplicate rectangular polyethylene ponds (measured 7 × 3 × 1 m) at an initial stocking density of 105 fish per pond. The fish were fed one of the following regimes: the 1st is a commercial floating diet (CFD, 30 % crude protein; T1), the 2nd is a combination of 50 % CFD: 50 % AMFS (T2), the 3rd is a solo of AMFS (T3). Water quality parameters did not differ significantly among different treatments except for a significant reduction in total ammonia nitrogen and a higher zooplankton count in the water of the AMFS group. The fish reared with AMFS as a solo feed (T3) experienced a significant growth performance, somatic indexes, and digestive enzyme activities compared to the fish reared in other treatments. Fish fed AMFS alone (T3) or in combination with CFD (T2) had an improved hematological profile, liver and kidney function indicators, serum lipid, and protein profiles than those fed CFD (T1). Histological and histometric analysis of the intestine showed an improved architecture with AMFS feeding. Furthermore, AMFS feeding increased the diameter of muscle bundles and the protein content of the dorsal muscles. The flesh quality parameters, including water holding capacity, stored loss, drip loss, and frozen leakage rate were improved in fish fed on AMFS alone or in combination with CFD. Therefore, from the above-mentioned beneficial effects of AMFS, it could be used as a promising, economical, and sustainable technology for rearing L. carinata.