Cellgevity® is a supplement reported to comprise mostly D-Ribose and L-Cysteine enriched glutathione, known to be an effective antioxidant that improves spermatozoa quality. However, its effect on milt characteristics has not been reported. This study, therefore, aimed to evaluate the effects of Cellgevity® on the milt quality of catfish (Clarias gariepinus) extended in sodium citrate during chilled storage. Pooled milt sample from three fishes was divided into three groups (T1, T2 and T3). The milt was extended in sodium citrate, and each group in triplicate was supplemented with Cellgevity® at 0 mg (T1), 125 mg (T2) and 250 mg (T3). The spermatozoa motility, concentration, viability and morphology were evaluated on days 0, 1, 2, 3, 4 and 5 of chilled storage. Data were expressed as mean ± standard deviation (SD) and analysed with a one-way analysis of variance (ANOVA) followed by Dunnett's multiple comparison test. Mean ± SD spermatozoa motility was significantly (P < 0.001) lower in T2 and T3 than T1 before and during the first 3-days storage period. Mean ± (SD) spermatozoa concentration was significantly (P < 0.001) higher in T2 and T3 than T1 before and throughout the 5-days storage period. Mean ± SD live spermatozoa were significantly (P < 0.001) lower in T3 than T1 at day 2 of the storage. Mean ± SD total abnormal spermatozoa did not differ significantly (P > 0.05) among the groups before and throughout the 5-days storage period. It was concluded that although supplementation of Cellgevity® at 125 mg and 250 mg in milt of catfish, extended in sodium citrate in chilled storage maintained the sperm cells alive and motile up to four days of the storage. However, it did not improve the milt quality. Hence, it should not be supplemented in sodium citrate extended milt of catfish, Clarias gariepinus in chilled storage.