The Mass Culture of the Freshwater Rotifers Brachionus Rubens Ehrenberg 1838 Using Different Algal Species Diets

The bottleneck of most inland freshwater aquaculture enterprises is in obtaining an adequate number of fingerlings, due to their high mortality at early life stages. Their successful production is hindered by many factors including an adequate supply of food at early larval stages. A study on the mass culture of freshwater rotifer species was conducted at the freshwater rotifers’ laboratory in Cần Thơ University’s College of Fisheries and Aquaculture. Brachionus rubens Ehrenberg 1838 were identified and inoculated in 30 identical Falcon cups of 50 ml at 5 female rotifers cup⁻¹ in order to obtain cultures with sufficient rotifer density for the subsequent culture experiments. A feeding experiment to identify the algae diet that conferred the best culture performance was conducted. Four different feeding treatments involving monodiets of Nannochloropsis oculata, Chaetoceros calcitrans and Chlorella vulgaris algae species and additionally a mixture of the three algal species were run in a 7-day experiment period. 1.5 l of identical, transparent plastic bottles filled with 1 l of mineral bottle water were stocked at an initial density of 20 individual rotifers ml^⁻1 were used in three triplicates. Water temperature and water pH were 26 ± 1 ^°C and 7.5 ± 1.5 respectively. The diet containing mixed algal species had significantly higher rotifer density and egg ratio on the 7^th day. Blending microalgae species can enhance the culture performance of the freshwater rotifers B. rubens when compared to monospecific microalgae diets.