Assessing the effects of dietary and waterborne commercial salt on the performance and welfare of common carp

Abstract

This study investigated the effects of salt additives in water and diet on the physiological and health parameters of common carp (Cyprinus carpio L.). Fingerlings (~50 g) were divided into seven groups: a control group (G1), three water treatment groups (G2_A–_C; 4, 8, and 12 g L⁻¹ salt), and three diet treatment groups (G3_A–_C; 5, 10, and 15 g kg⁻¹ dietary salt). All fish were fed a standard diet containing 28% crude protein at 3% body weight per day. Results revealed that G1 had the highest values for lymphocyte and monocyte counts, mean corpuscular hemoglobin (MCH), mean corpuscular volume (MCV), cholesterol, triglycerides, low-density lipoprotein cholesterol (LDL), albumin, total protein, and several somatic indices. G2_B exhibited significantly higher potassium and sodium levels, while G3_A showed elevated white blood cell (WBC), granulocytes, liver enzyme activities (Alanine aminotransferase activity (ALT), aspartate aminotransferase activity (AST)), creatinine, glucose, chloride, and various somatic indices. G2_A and G2_B groups had increased red blood cells (RBC), hemoglobin, hematocrit, and body weight index. The findings indicate that using 12 g L⁻¹ salt in rearing water and 15 g kg⁻¹ salt in the diet can enhance growth and health performance in Cyprinus carpio. This study provides important insights into salt-induced physiological responses in carp and offers practical recommendations for aquaculture practices.