Document Type : Primary Research paper
This article reports a survey of parasites in wild glass eels following them through culture to elvers in over-flow and re-circulating water systems in Vietnam. The results show that wild glass eels are infected with three parasitic species (Trichodina sp., Ichthyophthirius multifilis and Pseudodactylogyrus anguillae). Eels in re-circulating systems are infected with three parasites (Trichodina acuta, Trichodina sp., and Pseudodactylogyrus anguillae). Seven parasitic species were found on/in eels in the over-flow system (T. acuta, Trichodina sp., I.multifilis, P. anguillae, Pseudodactylogyrus bini, Centrocestus formosanus (metacercaria), and, Haplorchis taichui (metacercaria). Two parasites, Trichodina sp., and P. anguillae, were found on wild glass eels and elvers in both rearing systems. T. acuta had the highest prevalence (57.3%) in the recirculating system. P. bini had the highest prevalence (56.1%) in the over-flow system. The prevalence of Trichodina sp. infected fish in the recirculating system was 39.6%. That of C. formosanus (metacercaria) was 10.6% in the over-flow system. The prevalence of other parasites in all habitats was less than 10.0%. Two out of 3 parasites found in the re-circulating system had higher prevalence than those in the over-flow system. Results show that elvers reared in over-flow water systems had more parasites than wild glass eels or those reared in recirculating water system.