Parasite Nerocila acuminata
Taxonomy Arthropoda, Malacostraca, Isopoda
Hosts Black porgy (Acanthopagrus schlegeli), Bermuda porgy (Diplodus bermudensis), Creole-fish (Paranthias furcifer)
Infection site Caudal peduncle
Clinical sign A pair of parasites (male and female) is observed on the caudal peduncle (Fig. 1).
Parasitology Male (Fig. 2: right) and female (Fig. 2: left) are ca. 2.0 cm and ca. 2.5 cm in length, respectively. For attachment, Nerocila acuminate uses peraeopods, which are inserted into host muscle (Momoyama and Tensha, 2006).
Pathology Host tissues are eroded and epithelial hyperplasia is pronounced at attachment site. The body color of lesion changes due to the localized loss of dermal melanophores (Rand, 1986).
Health hazard Since this parasite is not infectious to human, it is harmless in food hygiene.
Diagnosis Check the parasite on the caudal peduncle.
Other information Rhexanella verrucosa infecting to the buccal cavity of red sea bream Pagrus major and Mothocya (=Irona) melanosticta infecting to the gill of Japanese halfbeak Hyporhamphus sajori are known as related species to the present parasite.
References Momoyama, K. and K. Tensha (2006): Ugly-looking parasitic infections and other abnormalities of wild fish and shellfish caught in the coastal or inland waters around or in Yamaguchi Prefecture. Bull. Yamaguchi Pref. Fish. Res. Ctr., 4, 143-161.

Rand, T. G. (1986): The histopathology of infestation of Paranthias furcifer (L.) (Osteichthyes: Srranidae) by Nerocila acuminata (Schioedte and Meinert) (Crustacea: Isopoda: Cymothoidae). J. Fish Dis., 9, 143-146.

(Photos by K. Momoyama)

Fig. 2. Female (left) and male (right) of N. acuminata.

Fig. 1. Nerocila acuminata parasitizing the caudal peduncle of black porgy.