Phytobiotics can be described generally as a term applied for algae or aromatic plants and
essential substances or oils extracted from them, which help to increase the growth performance
and have antimicrobial activity to replace the addition of antibiotics in feed of animals. Blue
green algae, Spirulina platensis (Sp. platensis) can be attributed to the group of phytobiotics as
it can be used as a food supplement [1] as it is a rich source of nutrients such as vitamins,
minerals, carbohydrates, and γ-linolenic acid [2] and a good source of protein [3]; help in the
development of potential pharmaceuticals [4] and finally has antioxidant properties [5]. Studies
indicated the usefulness of Spirulina for partial or complete replacement of fish meal in the diets
of two Indian major carps, Catla (Catla catla) and rohu, (Labeo rohita) [3] and up to 40% of the
fish meal protein in Nile tilapia diets [6]. The dietary Spirulina has immune potentiating effects
on the Carp (Cyprinus carpio L.) [7] and Nile tilapia, Oreochromis niloticus (O. niloticus)[8].
Oregano essential oil (OEO) that extracted from O. heracleoticum L. plants are characterized by
a high phenolic content (Carvacrol and thymol comprising 78.27% of the total oil) and two
monoterpene hydrocarbons, γ-terpinene and ρ-cymene (5.54 and 7.35% of the total oil,
respectively) [9]. The dietary Oregano oil improved not only the growth performance, muscle
protein content and feed utilization but also the survival rates and disease resistance of shrimp
[10], Nile tilapia fingerlings [11]; Channel catfish (Ictalurus punctatus)[12]; Common carp
(Cyprinus carpio L.) and farmed gilthead seabream (Sparus aurata)[13]. In this study, cultured O.
niloticus groups were fed on a diet containing different concentrations of Jade Spirulina® and