Abstract
•Yucca schidigera extract was for the first time to be experimented on the European seabass.•Yucca positively influenced the health status of the cultured European sea bass juveniles.•The tested levels of yucca reduced substantially the ammonia in water with no adverse effects on fish.•The welfare of Dicentrarchus labrax juveniles might be achieved at 0.75 mg L−1 yucca liquid extract.
As an herbaceous plant containing high levels of steroidal compounds in its branches and leaves, Yucca schidigera, in addition to being used as a food supplement, has shown promising activity in the adsorption of harmful compounds such as ammonia. A total of 180 Dicentrarchus labrax juveniles (initial body weight of 5.0 ± 0.5 g/fish) were allocated randomly in twelve glass aquaria (70 × 40 × 30 cm) with 15 fish per aquarium (four treatments, in triplicate). Three yucca liquid extract levels in water (0.25, 0.5 and 0.75 mg L−1) were established to examine the potential for reduction of ammonia levels and the survival and physiological parameters of European seabass juveniles. The results indicate that the yucca liquid extract significantly reduced the total ammonia nitrogen levels derived from fish excreta and uneaten feed to 0.07 mg L−1, diminished the mortality of seabass to 3%, and increased the dissolved oxygen concentration to 6.29 mg L−1. Haematological and physiological parameters were improved significantly (P < 0.05) with increasing yucca liquid extract levels. As a result of haematological response enhancement, the growth performance increased significantly (P < 0.05) with increasing yucca liquid extract levels in water. The current study revealed that the use of liquid extract of Y. schidigera at a concentration of 0.75 mg L−1 effectively reduced the ammonia concentration in ground-well-derived rearing water and was beneficial to the growth of, improved the physiological responses of and decreased the mortality rates of European seabass juveniles (D. labrax).