The marine copepod species Oithona nana is considered as one of the most successfully mass cultured Cyclopoida species in marine hatcheries. This study investigated the effects of four feed diets (soybean, yeast, rice bran, and corn starch) on the population growth, growth rate, population composition, fecundity, and fatty acid composition of native isolated Cyclopoida copepod species O. nana. The experiment was continued for 15 days and the copepods were fed on one of the four diets with a concentration of 1 g 10−6 individual day−1. The results revealed that corn starch was found to be the most supportive diet for population growth and population growth rate. For nutritional value, copepods fed on rice bran were detected to have the highest content of MUFA, PUFA, and the lowest SFA and SFA/UFA ratio; more importantly, the rice bran diet was the only treatment that showed C20:5ω3. Moreover, copepods fed on rice bran showed the highest significant female fecundity, copepodite, and nauplii percent. Finally, the protocols described in the current study concluded that the dry feeds, especially corn starch, are very useful and applicable in hatcheries for maximizing the fecundity and density of Cyclopoida copepod species, O. nana.

Copepods are one of the most abundant and diverse live food sources for mesopelagic and bathypelagic fishes and crustaceans. They could contribute to the overlap of the transition period from live feed to an artificial weaning diet in marine larvae production. However, the culture conditions still need optimization to provide sufficient production to cover the increasing demand for marine hatcheries. Therefore, the present study investigated the effects of different salinity levels (5, 10, 15, 20, 25, and 30 ppt) on the population growth, growth rate, and population composition (males, females, copepodite, and nauplii ratio) of the marine copepod, Oithona nana. The experiment continued for 15 days, under laboratory-controlled conditions of temperature (27 ± 1 °C), pH (7.7 ± 0.15), and continuous gentle aeration in 30 L glass aquaria. The copepod culture aquaria were supplemented with a mixture of soybean and yeast (0.5 g 10−6 individual−1 24-h−1) as a feed source. The highest significant population growth and population growth rate of O. nana were achieved with a salinity level of 20 ppt. Regarding population composition, O. nana cultured at the salinity level of 20 ppt recorded the highest significant percentages of copepodite and nauplii. The results concluded that copepod, O. nana, is capable of withstanding abrupt changes in the salinity, but there are limits to their tolerance, with an optimal salinity level of 20 ppt. This salinity level achieved the highest population growth and the highest percentages of copepodite and nauplii of marine Copepoda, O. nana.