Evaluation of some commercial water additives of probiotics and yucca on water quality, blood biochemistry, sex hormones, reproductive and fry performance of Nile tilapia ( <i>Oreochromis niloticus</i> ) that were reared under unchanged water

In accordance with achieving the principle of sustainable development and facing the challenges of fresh water scarcity, this study is one of the first studies of tilapia fish hatching under unexchanged water system with using Probiotics and/or Yucca as a water additive on reproduction and productive performance of Nile tilapia broodstock. Four experimental groups were examined; group1: control without any water the addition; group 2: addition of 2g/tank/week commercial probiotic (Ammo-CARE); group 3: addition of 2 cm/ tank/ week commercial yucca (AQUA-YUCCA); group 4: addition of 2g/tank/week commercial probiotic and yucca together (UNI ECOTREAT). A 72 broodstock (48 females and 24 males) were distributed in rectangular fiberglass tanks (1.5 m3) with three replicates for each treatment, each tank stocked with six broodfish (4 females: 2 males). Results illustrated significant changes (P≤0.05) among groups in most measurements. The treated group with probiotic and yucca together had the best physiological status of blood biochemical, blood gases, and sexual hormones in females and males broodstock, also it had the highest relative fecundity (974.50), absolute fecundity (5.61) and gonad somatic index (3.74 %) followed by Yucca, probiotics and control groups. In the same trend, the total fry production/ tank was 4500, 4000, 1820, and 1535 respectively. Furthermore, a treated group with probiotics and yucca together had a positive effect on fry performance and recorded the highest values of specific growth rate (9.12%day-1) and survival rate (87%) followed by treatments of Youcca, probiotics, and control respectively.