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The aim of the experiment was to study the amount of oil-producing Rhodotorula strain PR61 as fish feed additive and the effect of wall breaking treatment on feeding effect. A total of 375 red crucian carp seedlings with an average body weight of 4~5 g were randomly divided into five groups with three replicates per group and 25 fish per replicate. Fish in blank control group were fed with 100% basic feed, fish in positive control group were fed with 100% basic feed + 0.25% betaine hydrochloride, fish in T1 group were fed with 99.5% basic feed + 0.5% unbroken red yeast, fish in T2 group were fed with 99.5% basic feed + 0.5% broken red yeast, and fish in T3 group were fed with 99% basic feed + 1.0% broken red yeast. The experiment lasted for 28 d. The results showed that the PR61 strain was rich in nutrition, with protein content up to 45.2%, oil content up to 38.93%, the PR61 strain also contained carotenoid, aspartate, serine and totally 17 kinds of amino acids, and the total amino acid was 44.32%. The survival rate of red crucian carp in T2 group and T3 group was 100%, which was significantly higher than that of blank control group and positive control group (P<0.05). The body weight growth rate of red crucian carp in T3 group was significantly higher than that in other groups (P<0.05), the body length growth rate was significantly higher than that in blank control, positive control group and T1 group (P<0.05), and the feed coefficient was significantly lower than that in other groups (P<0.05). The a* value and L* value of the back skin of red crucian carp in T3 group were significantly higher than those in other experimental groups (P<0.05). The activity of SOD and GSH-Px in serum of red crucian carp in T2 group and T3 group were significantly higher than those in other groups (P<0.05), and the content of MDA was significantly lower than that in other groups (P<0.05). The CAT activity of red crucian carp in T3 group was significantly higher than that in blank control, positive control group and T1 group (P<0.05). The study indicates that adding PR61 in feed can significantly improve the survival rate, weight growth rate and antioxidant enzyme activity of fish fry, decrease the feed coefficient. The growth index of the fish fry reaches the best level and the color of fish body is more vivid when the supplemental amount of red yeast is 1.0%. [ABSTRACT FROM AUTHOR]