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In recent years the use of rotifers as live food for rearing fish larvae and crustacean is very important. Growth and density is considered as an important factor in the production of rotifers. In this study, the effect of three different concentrations (1.5×106, 3×106, 4.5×106 cell/ml-1) of green algae, Tetraselmis Suecica, on growth, reproduction, body and egg size of marine rotifer, Brachionus plicatilis were investigated. Rotifers were cultured in standard conditions in 500 ml plastic containers. The initial density of rotifers in different treatments was 30 ind/ml. Based on the results, the highest density (331/67 ± 13/32) were showed in high concentration, which were significantly (P <0/05) higher than the other two treatments. Specific growth rate at concentrations of 3×106 cell/ml-1and 4.5×106 cell/ml-1 were significantly greater than concentrations of 1.5×106 cell/ml-1 of green algae (P<0.05). However, no significant differences were observed between the two treatments, medium and high. The maximum number of eggs and egg-bearing females were observed in the fourth and seventh days. Mean body size (lorica area) and egg size (bio-volume) in rotifers fed with high concentrations (4.5×106cell/ml-1) significantly greater than the mean body size of rotifers fed with medium (3×106 cell/ml-1) and low (1.5×106 cell/ml-1 ) concentrations while no significant differences were observed between low and medium treatments(P>0.05). The present study showed that the concentration of algae Tetraselmis suecica might be used in marine rotifer breeding and changing various concentrations, can produce various sizes of rotifers.

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In this work, the paste of microalga, Tetraselmis suecica, was produced and the effects of vitamin C and E on its food value and shelf life improvement during eight weeks of storage in refrigerator (4°C) was investigated. The microalga was initially mass grown up to logarithmic phase in standard convey medium, then concentrated by cream skimmer centrifugation method. The obtained algal paste was treated by adding vitamins C, E and their mixture (all 0.1% weight/weight), and refrigerated for 8 weeks. The density of algal cells was1.38109 cells/ml and the production yield was about 1.7 gr/l. The cell viability in vitE-treated pastes (39/99±2/1%) was higher than the control group (p>0.05), indicating the positive effect of the preservatives. The proximate analysis showed that the control group had the lowest moisture (86.8 %), the vit C-treated group had the highest protein (36.6%) and lowest ash (29.9%), and the mixture of vits-treated group had the highest fat content (13.4%) at the end of the storage period. pH in the control and vit- C treated groups was lower than the other two treatments (p>0.05). In conclusion, using of vitamins E and C as well as refrigerator storage are suggested for qualitative preservation of T. suecica algal paste.