First detection of Megalocytivirus (Iridoviridae) in trash fish used for aquaculture feed in Sabah, Malaysia

Document Type: Primary Research paper

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Abstract

Trash fish is a popular aquaculture feed in Sabah, Malaysia. Among the many fish species, Indian mackerel (Rastrelliger kanagurta), spotted sardine (Sardinella sp.), smoothbelly sardine (Ambligaster leiogaster), mackerel scad (Decapterus macarelus), round scad (Decapterus sp.) and big eyed scad (Selar crumenopthalmus) are the most commonly used trash fish. However, the increasing number of disease outbreaks occurring throughout aquaculture farms has prompted us to conduct this study with the aim to determine if Iridovirus presents in six different species of trash fish namely; Indian mackerel, spotted sardine, smoothbelly sardine, mackerel scad, round scad and big eyed scad collected throughout Sabah. In this study, DNA from 230 fish specimens was subjected to nested-PCR and DNA sequencing analyses. The results showed 15.22% of specimens were found to have been contaminated with Infectious Spleen and Kidney Necrosis Virus (Megalocytivirus, Iridoviridae). This indicates that trash fish can harbor viral pathogen and may likely to transmit it to culture fish during feeding. The reliance on trash fish for aquaculture feeding can jeopardize the sustainability of the aquaculture industry. Therefore, the use of pellet feeds made from certified virus-free ingredients may be the best choice to minimize viral outbreaks.   

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