International Journal of Aquaculture, 2024, Vol.14, No.1, 9-19 http://www.aquapublisher.com/index.php/ija 10 shrimp, copepods, and rotifers is thus vital for the successful fry production of different fish species in aquaculture (Abaho et al., 2016). Amongst the live starter feeds, copepods are known to be nutritionally superior as they contain higher levels of Docosahexaenoic acid (DHA) and a protein content of 44%~52% with a suitable amino acid profile (Radhakrishnan et al., 2020). Additionally, the copepodites and adults have digestive enzymes required in the early life stages of fish and crustacean larvae (Alejos et al., 2022). The size suitability of nauplii and early copepodite stages of copepods are easily utilized by small-sized larval fish compared to Brine shrimp and rotifers during larval fish nutrition (Chepkwemoi et al., 2013). Copepods classes include Calanoid, Harpacticoid, and Cyclopoid copepods. Among these classes, Cyclopoid copepods are advantageous in different ways; they are easy to culture and can be maintained in higher densities compared to Calanoids (Park et al., 2021). Also, the presence of the paired egg sacs attached to the female genital segment means that higher production of Cyclopoid copepods is achieved compared to Calanoids (Mironova and Pasternak, 2017). The short development times of 4-5 days to maturation for copepods make them ideal to use in the mass culture and subsequent feeding of the fish larvae (Chepkwemoi et al., 2013). Therefore, all these advantages make the cyclopoids better copepods for larval nutrition. In the family Cyclopidae, Thermocyclop sp. is dominant. The species is distinguishable from other copepods by the first antennae, which are shorter than the combined length of the head and thorax, along with the uniramous second antennae (Chepkwemoi et al., 2013). Thermocyclops sp has a wide distribution in freshwater systems including lakes, rivers, and marshes (Jaime et al., 2021). The species is predominantly pelagic thrivings in littoral zones characterized by dense stands of immersed macrophytes. The Thermocyclop sp. also tolerate salinities of up to 7.2% and pH, ranging from 5.9 to 8.4. Ecologically, the species plays a pivotal role as the primary link connecting phytoplankton's primary production to higher predators, including shrimps and juvenile fish (Abaho et al., 2016). Besides, these organisms can elongate essential fatty acids to produce polyunsaturated fatty acids (DHA and EPA), which are required for the physiological functioning of fish (Chepkwemoi et al., 2013). These unique qualities provide a competitive advantage for Thermocyclop sp. as an ideal food source in larval fish culture. Although copepods present a competitive advantage as crucial live starter feeds in aquaculture, their appropriate storage conditions have not been thoroughly explored (Chepkwemoi et al., 2013; Abaho et al., 2016; Beingana et al., 2016; Izaara et al.; 2020). For example, sustaining their availability for use in hatcheries is still challenged by inadequate information on ideal storage temperatures and densities in the Ugandan aquaculture industry. Therefore, the present study explored the effects of storage conditions (temperature and density) on the survival and fatty acid profiles of Thermocyclop sp. It was hypothesized that the manipulation of the storage density and temperature of Cyclopoid copepods (Thermocyclop sp.) results in variations in survival rates and fatty acid profiles of the copepods. The successful storage and packaging of live Thermocyclop sp. will enhance their accessibility and utilization in fish hatcheries as alternatives to the presently commonly used Artemia in Uganda. The results from this study will directly impact larval fish nutrition by providing insights into how storage conditions influence the fatty acid profiles of copepods. This information can be translated into practical recommendations for ensuring that larval fish receive the best possible nutrition during their critical early stages. Subsequently, interventions will bridge the supply gap to live starter feeds thus contributing to the growth of aquaculture in Uganda. 1Results 1.1 Survival rates Generally, there was a gradual decrease in the survival rate of Thermocyclop sp. at different temperatures with time. The percentage survival rates of Thermocyclop sp. were significantly higher at 12 °C than at 4 °C (Figure 1) (2 = 9.9, df = 2, P= 0.007). Percentage survival after 14 days was 55.7 ± 0.9% (12 °C), 44.0 ± 1.5% (8 °C), and 30.7±1.2% (4 °C).
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