Food intake, survival, and immunity of Nibea albiflora to Cryptocaryon irritans infection.

Cultured Nibea albiflora rarely die from cryptocaryoniasis. To explore the resistance of N. albiflora against the invasion of Cryptocaryon irritans, in this study, 40 g N. albiflora was artificially infected with C. irritans at a median lethal concentration (2050 theronts/g fish). The food intake, survival, relative infection intensity, and immobilization titer variation of serum and mucus at different time points after the infection were compared. Results showed that the ingestion of N. albiflora could be resumed only 1 day after feed deprivation by the disease, which indicated the quick resilience of N. albiflora. N. albiflora did not die out even if it was cultured continually for up to 15 days at 27 °C in a culture tank with a large quantity of C. irritans tomonts. It was because that, without any exterior force, N. albiflora could block the C. irritans cell proliferation, and then the pathogens disappear gradually. In vitro immobilization titer test results confirmed that the serum and mucus could directly eradicate C. irritans.