Potential benefit of I-Tiao-Gung (Glycine tomentella) extract to enhance ornamental fish welfare during live transport

Abstract

Multiple stressors associated with live fish transport, such as shaking, packing, hyper‑oxygenation, and cold stress, present a growing concern for fish welfare. The current study was designed to evaluate the fish welfare promoting effects of I-Tiao-Gung extract (Glycine tomentella, GTE), an extract derived from a Chinese herb, during live transport of blood parrot cichlid (Amphilophus citrinellus x Cichlasoma synspilum) and koi (Cyprinus carpio). The study analyzed plasma electrolytes, glucose, lactate, and cortisol levels from blood of both fishes during simulated transport. Results showed that adding GTE in water significantly decreased cortisol levels in blood parrot cichlid after 2–6 h and in koi after 4–6 h of simulated transport, respectively. Levels of glucose, lactate, and K+ in blood parrot cichlid began to elevate significantly between 2 and 6 h under stress. While levels of blood Na+, Ca2+ and lactate of koi significantly increased after simulated transport. Interestingly, Cl− levels were depressed significantly upon stress in both fishes. An indirect approach using ventilation frequency (VF) to gauge metabolism was taken to assess the physiological effects. VF was significantly slower in blood parrot cichlid after GTE addition comparing to that of the control group, but the effect was not significant in koi. Therefore, addition of GTE mitigated transport stress responses in both ornamental fishes through down-regulation of cortisol; thereby, promoting fish welfare during live transport.