This study aimed to evaluate the effect of lutein supplementation on growth, survival and skin pigmentation for goldfish juveniles. Four diets enriched with different carotenoid sources (lutein, astaxanthin, canthaxanthin and a combination of lutein and canthaxanthin) were compared to a control diet without carotenoid supplementation. The carotenoid inclusion level was standardized at 50 mg kg‐1 in all treatments. 240 goldfish juveniles (1.07�0.57 g) were cultivated in 30 aquariums (30L) during 84 days. The experimental design was completely randomized with five treatments and six replicates. The dietary inclusion of carotenoid pigments did not affect the growth and feeding efficiency of goldfish juveniles. Supplementation with lutein presented higher survival values when compared to the other treatments. Astaxanthin and canthaxanthin supplementation increased the concentration of carotenoids on the skin of goldfish juveniles in relation to the control treatment. For the fish fed with the diet containing lutein, the skin pigmentation was as efficient as astaxanthin and canthaxanthin, but did not differ from the control and combined treatment (canthaxanthin + lutein). The lutein supplementation (50 mg kg‐1) improved survival and promoted efficient carotenoid pigmentation on the skin of goldfish juveniles.

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This study evaluated the effects of different dietary inclusion levels of fermented soybean meal (FSM) as replacement for fish meal and their effects on the productive performance and intestinal condition of goldfish (Carassius auratus) produced in biofloc (BFT) system. Five isoproteic (39.5% crude protein) and isoenergetic diets (4250 kcal kg −1 of crude energy) were formulated with FSM inclusion levels of 0%, 7%, 14%, 21% and 28% (0, 11, 22, 32 and 43 fish meal replacement). A total of 400 goldfish (0.25 ± 0.02 g) were weighed and distributed in 20 glass aquariums (15 L). Fish were fed twice daily for 56 days. The diet with FSM inclusion level of 28% reduced the weight gain and the specific growth rate and increased the feed conversion of the goldfish. Diets with FSM inclusion levels of 21% and 28% increased the α-amylase activity in the fish intestine. The diet with FSM inclusion level of 21% increased total height of the intestinal villi of the goldfish. In conclusion, the inclusion of up to 21% of FSM can replace fishmeal without affecting the growth of goldfish juveniles reared in BFT system. Fish fed 21% of FSM showed evidence of improvement in the intestinal health.

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