The objective of this study was to compare the effects of four astaxanthin preparations with different ratio of E/Z (trans/cis) isomers and different coating materials on the pigmentation and antioxidation properties of rainbow trout. Five diets were designed as basal diet (without astaxanthin supplementation) and four astaxanthin diets (100 mg/kg diet) supplemented with four astaxanthin products, BASF (79% all‐E, gelatin coated), Wisdom‐B (85% all‐E, gelatin coated), Wisdom‐C (94% all‐E, carrageenan coated), and Wisdom‐D (94% all‐E, gelatin coated). After 4 wk feeding, the flesh astaxanthin content, redness, and yellowness of astaxanthin‐supplemented groups were higher than those of control group at the second and fourth week (P < 0.05). Among these astaxanthin‐supplemented groups, the Wisdom‐B group had the highest flesh redness and astaxanthin content. The astaxanthin‐supplemented groups also had the lower flesh frozen loss and malondialdehyde level than control group at the fourth week (P < 0.05). The results indicated that dietary 100 mg/kg astaxanthin could improve the flesh redness and antioxidation abilities of rainbow trout. The ration of E/Z isomers and properties of coating materials of astaxanthin preparations influenced the pigmentation and antioxidation properties, and Wisdom‐B had a better pigmentation effect on the flesh than other astaxanthin preparations.