This experiment was conducted to evaluate the effect of Padina astraulis extract on the growth performances (final weight (FW) and daily growth ratio (DGR)), feed indices (feed conversion rate (FCR), voluntary feed intake (VFI), protein efficiency ratio (PER) and lipid efficiency ratio (LER) and body chemical (protein, fat, moisture and ash) and fatty acid profile of Mugil cephalus for 62 days. The experiment was conducted in a completely randomized design with 360 of Mugil cephalus larvae (with average weight of 0.82±0.02g) in 4 treatments and 3 replicates (n=30 in each replicate) and included: control group without using algae extract, an another groups (treatment 2, 3 and 4) the amounts of this extract were 5,10 and 15 g/kg food. The results showed that at the end of experiment, the highest FW (4.22±0.11g), DGI (1.77±0.51%), the lowest FCR (0.95±0.05), the highest VFI (2.81±0.12 %), the highest PER (2.91±0.78), the highest LER (3.66±0.54), the highest crude protein (23.51±0.98%), the highest crude lipid (18.95±0.08%) and the highest poly unsaturated fatty acid (PUFA) including C18:2n-6 (6.51±0.04%), C18:3n-3 (4.81±0.09%) and C20:5n-3 (EPA) (5.21±0.10%) were observed in the diet containing 15 g /kg algae extract in all of these parameters, treatment 4 showed a significant difference compared with control group (P<0.05). Finally, the present findings revealed that diet containing 15 g/kg Padina astraulis could improve growth, feed performances, carcass quality and increase PUFA level in Mugil cephalus larvae.