Caulerpa lentillifera is a green alga that contains essential nutrients. This study investigated the effects of autoclave- and microwave-assisted C. lentillifera extracts (A-CLE and M-CLE) on the growth, reproduction, immunity, and oxidative stress in Daphnia magna. Both extracts were supplemented to D. magna at 1 to 5 g/L. The results showed that D. magna treated with 2 to 5 g/L of A-CLE produced juveniles faster than the control. Juveniles at 1 to 4 g/L A-CLE treatments increased. Moreover, juveniles in 1 g/L M-CLE treatment significantly increased, but the hatching time was not affected. A-CLE also stimulated the immunity of D. magna by increasing hemocytes in the 3 g/L treatment. Furthermore, both extracts did not affect the growth rate, phenoloxidase activity, malondialdehyde level, and catalase activity in D. magna. Therefore, our results indicated that both extracts could enhance the reproduction and immunity of D. magna. Our study is useful for the health improvement of D. magna. [ABSTRACT FROM AUTHOR]