Dietary use of Spirulina (Arthrospira) and Chlorella instead of fish meal on growth and digestibility of nutrients, amino acids and fatty acids by African catfish

Growth performance and apparent digestibility coefficient (ADC) of fatty acids, amino acids and macronutrients for diet containing fish meal, Chlorella vulgaris or Spirulina platensis (=Arthrospira platensis) by African catfish (Clarias gariepinus) were assessed in a 42-day feeding trial using a fishmeal-based control diet (REF) and two other test diets containing Spirulina or Chlorella replacing fishmeal in the control diet. The Spirulina-based diet exhibited higher ADC of crude protein than the Chlorella-based diet. The Spirulina- and Chlorella-based diets exhibited higher ADC for all essential amino acids (EAA) when compared with the control diet. High methionine and lysine ADC of Spirulina and Chlorella diet were also observed. The Chlorella diet was significantly higher in ADC of histidine, arginine, valine, isoleucine and tryptophan. Chlorella diet had the highest ADC values for n_6 and n_3 PUFA, lipid. The Spirulina diet exhibited significantly higher lysine, crude fibre, energy, dry matter carbohydrate and docosahexaenoic acid (DHA)ADCs than the Chlorella diet. EPA of reference diet was however, significantly more digestible than Chlorella but not in Spirulina.