Watery yucca (Yucca schidigera) additions and biofloc as closed water systems: an assessment of their effects on reproductive efficiency, biochemistry and blood gases, and fry performance of Nile tilapia (Oreochromis niloticus)
摘要
Global water scarcity is a growing concern, prompting aquaculture specialists to seek techniques for prolonged water quality maintenance. This study conducted an 84-day spawning trial of Nile tilapia broodstock followed by a 45-day fry rearing trial under four treatments: control A (CA, unchanged water), control B (CB, 50% weekly water change), yucca (unchanged water with daily Yucca schidigera extract addition), and biofloc. Broodstock were distributed in three replicates per treatment (1 male:3 females) in 1.5-m3 tanks. Fish were fed a 30% protein commercial diet at 1% biomass. Fecundity indices, gonadosomatic index, and blood sex hormones were measured 20 days post-trial initiation. Fry were collected and reared in separate tanks, fed 40% protein diet. Results showed that the biofloc group, followed by yucca and CB, exhibited the highest levels of blood sex hormones, improved liver and kidney functions, enhanced blood oxygen saturation, and lower ammonia and carbon dioxide levels. These factors contributed to higher reproductive efficiency and fry production with superior growth performance and survival rates compared to CA. Nile tilapia broodstock spawned under a biofloc system or an unaltered water system with Y. schidigera extract additions produced higher quality fry and demonstrated better physiological status and reproductive efficiency. Furthermore, Y. schidigera can complement biofloc technology, potentially improving growth and immune status of farmed fish through enhanced water quality parameters.