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In aquaculture, the method of fertilizing to increase live food (microalgae) in phytophagous fish ponds Hypophthalmichthys molitrix has disadvantages, including the fact that fertilizers have increased the population of microalgae of all types (toxic and non-toxic) without human control and as a result, it can cause unwanted growth of harmful algae. The warm-water fish located in the province were carried out. In this project, the growth rate was calculated by feeding the 100 g juvenile fish with the edible algae Diatoma and Chlorella added to the treatments. To implement this project, 100 young children of 90 g silver carp were stored in each of the ponds. Experiments were performed in circular concrete ponds with a diameter of 6 meters, water height of 1 meter with 3 ponds and no water change was performed during the test period. Then, the microalgae were added to the ponds containing the tested silver carp. The breeding period was 8 weeks experimental ponds with different microalgae composition (1: 70% Chlorella, 30% Diatoma, 2: 70% Diatoma, 30% Chlorella and 3: Control which is the natural composition of microalgae in the region) during the experiment were fed. Since little information is available on the feeding effect of feeding silver carp juveniles of several microalgae species with different abundance percentages, in this study the growth rate of silver carp in different densities of Diatoma and Chlorella algae in combination with different percentages in the pond environment was evaluated and at the end of the experiment, survival percentage, fish growth rate, specific growth rate and daily average growth were calculated. The results of this study showed that in the ponds where the fish were fed with water enriched with hand microalgae, they had different growths and also (P <0.05) with significant growth (P <0.05). Survival percentage, fish growth rate, specific growth rate and average daily growth) were higher. Also, accrding to this study, since one of the conditions for having healthy farmed fish is to have a healthy and proper nutrition, so it is necessary to increase the share of edible microalgae Diatoma and Chlorella in the breeding environment of these fish to produce more and quality Diatomaceous algae with chlorophyll have been used in this project for the first time in Iran. And although many studies have been done on the nutrition of phytophagous by phytoplankton, but all those phytoplankton were from the branches of chlorophyta and cyanophyta, and in this project, for the first time, an algae from the branch of diatoms was used.
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