Relative condition factor and parasites of the Bigeye grunt, Brachydeuterus auritus (Valenciennes, 1831) inhabiting the coastal waters off Tema, Ghana

Abstract

The marine ray-fined Brachydeuterus auritus is one of the most exploited and heavily consumed fishes of the tropical and sub-tropical waters of the eastern-central Atlantic. Fish microbial studies have raised awareness of parasites that can impact fish health, growth, survival, reproduction, and the possible transmission of fish-to-humans situations. The study assessed the well-being of this economically important fish and the prevalence of parasites that they harbour which potentially is of public health interest.. This cross- ectional study involved sampling of fish from June to December, 2016. A total of 424 B. auritus were collected of which 228 were males, 157 females and 39 being hermaphrodites. Data on their length and weight were taken and condition factors determined. Ectoparasites were isolated for identification using a compound light microscope by direct smear of mucous scraped from the skin, fins and mouth, whereas endoparasites were isolated from the gut. The length of B. auritus ranged from 9.70 to 22.20 cm, and weighed between 13.51 to 149.92 g. The correlation coefficient (r) between the log of total length and body depth of the sexes ranged from 0.960 - 0.970. Brachydeuterus auritus in this part of the coastal waters of Ghana showed negative allometric growth for both sexes. Most of the parasites isolated were parasitic crustaceans, such as Achtheres sp., Clinostomum sp., Cymothoa sp., Ergasilus sp., and Rhabdochona sp. which were recovered from the gills and mouth. Parasite density was higher in males than in females. Samples of intermediate sizes had the highest parasite prevalence, and also had the least parasite intensity. This study has contributed to the knowledge on the parasitic infestations associated with this economically important fish species and their potential roles and dangers in the fish-to-human transmissions. More education on proper handling and cooking of fish be given to farmers, traders and consumers, as well as control of piscivorous birds is to maximize profitability in fish farming.