Effect of dietary substitution of fish meal for marine crab and echinoderm meals on growth performance, ammonia excretion, skin colour, and flesh quality and oxidation of red porgy (Pagrus pagrus)

• We evaluated two ingredients: marine crab (MC) and sea echinoderm (SU) meals.
• SU and MC meals increase feed intake and final weight and decrease ammonia excretion.
• Feeding the two meals increased muscle contents of arachidonic (ARA) fatty acids.
• Crab meal and echinoderm meal promoted red and yellow skin colouration, respectively.
• Feeding marine crab meal delayed lipid oxidation of fish fillet.

The present study was conducted to evaluate the effect of feeding marine crab (SMC) meal and sea urchin (SU) meal on growth performance, ammonia-N excretion, skin colouration and final flesh quality and lipid oxidation of red porgy (Pagrus pagrus). Fish were fed with five diets: a control-diet (CD); two diets replacing 10% and 20% fish meal protein by protein from SMC meal (SMC10, SMC20), and two diets with 8% and 16% inclusion of SU meal (SU8, SU16). The inclusion of both SMC and SU meals increased fish appetite response reflected in a significantly higher feed intake and final weight. Results were even better for fish fed on SU diets, with improved feed conversion (FCR) and protein utilization (PER). Ammonia-N excretion rates decreased in fish fed on SMC20, SU8 and SU16 diets. Fish skin colouration improved by SMC meal inclusion, while SU meal promoted yellowness colouration in skin. Higher muscle content of arachidonic fatty acid (ARA), was concomitant with the increased level of SMC in diets. The same trend was also found in fillet of fish fed on SU meal diets, with the highest values in ARA content. Results of TBARS in raw fillets showed that the dietary inclusion of SMC meal delayed lipid oxidation compared to FM and SU diets during refrigerated storage.