Copepods are the largest zooplanktonic crustacean which are important link between phytoplanktons and the higher trophic levels in aquatic ecosystems and they served as live food in aquaculture industry. They have a great importance in aquatic feeding larvae because of high species diversity, high level of unsaturated fatty acids, protein, carotenoids, and having larva essential digestive enzymes in early stages of nutrition and wide size range (six naupliar and five copepodit stages). In respect to their importance in aquaculture industry, at present research, the effect of different algal and non-algal diets on growth, production and some biological parameters of freshwater copepod, Eucyclops serrulatus such as body size, fecundity rate, development period, in addition, its ingestion rate fed on two green algae species of Chlorella vulgaris , Scenedesmus quadricauda and finally feeding behavior and ingestion rate of Pterophyllum scalare larvae (Angelfish) while feeding by copepod E. serrulatus and cladoceran Ceriodaphnia quadrangula were investigated under laboratory conditions. For this, three experiments including; effect of different diets (five treatments including; algae S. quadricauda , cereal mixed powder, fish food powder (FFT, made by Faradaneh Company), cattle and poultry mixed manure and baker yeast ( Saccharomyces cerevisiae ) ; ingestio rate of E. serrulatus fed o two green alga; Chlorella vulgaris , Scenedesmus quadricauda and finally angelfish larvae ingestion rate fed copepod E. serrulatus and C. quadrangula (Angelfish larva in three age groups of 6,14 and 24 days after hatching; 3 different density of 2, 5 and 10 preys /ml from copepod E. serrulatus and C. quadrangula ) were designed. Results showed that fish food powder had the most suitable diet for copepod E. serrulatus culturing, because the most level of production (48.8±4.7 individual/female), specific growth rate (0.15 /day), the shortest doubling time of population (4.60 days), the highest body size (691.8 µm in length and 298.2 µm body width), the highest fecundity (18.6 eggs) and the shortest development period (8.3 days for naupliar and 11 days for copepodit stage) were obtained in this conditions. On the other hand, the highest ingestion rate (0.4 ×10 4 cells /h) in this copepod species were obtained while feeding by high density of C. vulgaris (154.3 × 10 5 cells /ml). Results of ingestion rate Key words: Live food, Copepods, Eucyclops serrulatus , Green algae, Ingestion rate, Angelfish larvae
