3. Results
3.1. Prevalence of infection
Out of the total 116 sampled striped trumpeter juveniles, 73% had
epitheliocystis. There was no significant difference between cohort A
held inside or outside, therefore these two groups of fish were pooled
and analysed together. The prevalence of epitheliocystis and densities
of cysts were different between cohorts and sampling times (Table 2).
Prevalence in fish sampled in spring from cohort A was 49.2%; while,
fish from cohort B had 100% prevalence at this time. By autumn, there
was 100% prevalence of epitheliocystis in fish from cohort A; no samples
from fish from cohort B were available at that time. The severity
of epitheliocystis, measured as the density of cysts in each gill section,
was significantly higher in striped trumpeter sampled in autumn
compared with those sampled in spring. For cohort A fish collected
in autumn had much higher cyst densities (134.93±15.81) than
those fish sampled in spring (0.39±0.08). Thus, the cyst densities
were more than 100 times in autumn higher than those from the
same cohort sampled in spring (t=−8.509, df 47.002, pb0.05,
Table 2).