The effects of dietary malic acid on growth performance and intestinal histomorphology in goldfish (Carassius auratus)

In the present study, the effects of dietary malic acid on growth and intestinal histomorphology of goldfish (Carassius auratus) was investigated. 120 goldfish (mean initial weight 14.62 ± 0.92 g) (Mean ± Standard Error) were divided into 4 treatments and 3 replicates. Treatments included different concentrations of malic acid 0 (control), 2.5, 5 and 10 g/kg diet. Fish feeding was carried out three times a day for 8 weeks. Fish biometry performed every two weeks and at the end of the experiment, six fish per each tank were sampled for histological study of the intestinal tissue. Results showed that there were not significant differences in final weight, percentage of body weight gain, specific growth rate, feed conversion ratio and condition factor between different treatments (P> 0.05). There were not significant statistical differences in the length of the villi, the diameter of the tunica mascularis and also the number of calyx in the intestinal tract between different treatments (P> 0.05). The results of the present study showed that the use of malic acid does not affect the growth performance and intestinal histomorphology of goldfish.