Differences in susceptibility to the skin fluke Benedenia epinepheli between Epinephelus bruneus, E-septemfasciatus, and a new hybrid grouper Kue-Tama, E-bruneus x E-lanceolatus

摘要

Interspecific hybrids of marine fish are becoming popular for aquaculture. The advantageous characteristics of hybrid fish include high growth rates, enhanced feed conversion rates, better appearance, high tolerance to environmental stress, and increased resistance to certain diseases. A new hybrid grouper Kue-Tama, female Epinephelus bruneus x male E. lanceolatus has recently been established. This hybrid showed significantly higher growth than that by E. bruneus and is considered a promising new species for aquaculture, especially in temperate areas where the slow growth of E. bruneus has prevented stable farming practices. The present study compared the resistance of Kue-Tama, its maternal parent E. bruneus and E. septemfasciatus, another popular grouper for farming, against the skin fluke, Benedenia epinepheli, which is a problematic parasite in grouper farming. The result of the cohabitation experimental infection showed that E. septemfasciatus was the most resistant to the skin fluke, followed by Kue-Tama and then E. bruneus. There appeared to be a negative relationship between the amount of mucus produced and the parasite intensity suggesting a resistance to skin flukes though the dry-weight of mucus collected from a given skin surface area did not differ between the three groupers. These results demonstrated that Kue-Tama has another favorable characteristic for aquaculture, in addition to their higher growth rate.