Introduction of Artemia nauplii during Chinese perch (Siniperca chuatsi) first feeding: Effects on larvae growth, survival, gene expression and activity of critical digestive enzymes

This study investigates the effects of first feeding regime on growing, survival, and gene expression (appetite, digestion, absorption, and growth) and digestive enzymes activity in Chinese perch (Siniperca chuatsi) larvae. The fish larvae at 3 days post-hatch (DPH), were fed with prey fry (newly hatched zebrafish Danio rerio)/Artemia naupli from 3 to 15 DPH for different time periods as follows: (A)only prey fry;(B) 3–5 DPH Artemia/6–15 DPH prey fry;(C) 3–7 DPH Artemia/8–15 DPH prey fry; (D) a combination of Artemia and prey fry. Final performance parameters (total length, body weight, survival rate), gene expression and digestive enzymes were measured and compared among treatments at 15 DPH. The groups fed only prey fry (group A) (53.67 ± 1.76%) and combination of Artemia and prey fry (group D) (61.22 ± 1.18%), respectively, showed significantly (P < 0.05) higher survival specific growth rate (SGRTL) than other groups. Brain expression of npy and agrp were not significantly affected under different feeding regimes. The groups fed with Artemia till 7 DPH followed by feeding with prey fry till 15 DPH (group C) showed significantly (P < 0.05) higher pomc and cck expression level than the other groups. The expression of amy, ctrb, and pl was significantly higher in larvae fed combination of Artemia and prey fry (group D). pep had a high expression level in both group A and D. The highest expression of two genes related to intestinal development and maturation (alp, lap3, anpep) were observed in the fish fed a combination of Artemia and prey fry, but there was no significant difference compared to group A. The expression of absorption and growth (mtor, pept1 and igf-1) increased with combination of Artemia and prey fry in larval diet (group D), indicating a more efficient functionality of digestive structures. In conclusion, feeding with combination of Artemia and prey fry could be suggested as an economical feeding regime for first feeding of Chinese perch larvae as comparable growth to prey fry were achieved, and better survival.