Effect of the parasitic isopod,Catoessa boscii(Isopoda,Cymothoidae),a buccal cavity parasite of the marine fish,Carangoides malabaricus

Objective:To examine the effect of isopod parasite Catoessa boscii(C.boscii)on Carangoides malabaricus(C.malabaricus).Methods:The host fish C.malabaricus infested by C.boscii were collected directly from the trawlers landed at Parangipettai coast during December 2008 to November2009.Data regarding the total length,width,weight and sex of the host fish were recorded.Effect of infestation on C.malabaricus,the length and weight data were analysed and host specificity of isopods was also examined.Results:During the sampling period,585 C.malabaricus were examined.Among them,218 specimens were found to carry 243 parasites.Three pairs of isopods(one male with one female)were recorded from the host fish and each pair was attached to the tongue in the buccal cavity of the host.Another pair was also found where the male and male,female and female isopod had settled on the tongue in the buccal cavity.Gross lesions observed in the buccal cavity of infested fish showed small pin-holes in the tongue region,through which dactyls of pereopod's penetrating claws dig into the host tissues.The maximum weight loss was reported in females(5.43%)than in males(3.75%)of C.malabaricus.Due to infestation of different isopod parasites in both male and female fish,the effects on the length-weight relationship of C.malabaricus were compared.The rate of increased growth in weight in uninfested female fish was found to be higher than that of the infested.The weight gain is faster in uninfested fish than in the infested fish.Conclusions:From the above mentioned observations,it is clear that the worst of fish on account of the infestation of isopods are the C.malabaricus succumbed to the attack of isopod parasites.Although,the infestation did not cause immediate death,it had affected the normal growth of the host fish.

Reproductive aspects of the coastal trevally,Carangoides coeruleopinnatus in Terengganu Waters,Malaysia

This study describes for the first time the reproductive biology of the coastal trevally(Carangoides coeruleopinnatus)(Ruppel,1830)caught from Terengganu waters,Malaysia.Monthly sample collection from April 2019 to March 2020 was done at Pulau Kambing fish landing port in Terengganu,Malaysia.A total of 687 individuals comprise of 362 males(52.69%)ranged from 6.3 cm to 26.6 cm(mean±SD:13.2±3.84 cm)and 325 females(47.31%)ranged from 9.0 cm to 26.4 cm(mean±SD:13.9±3.34 cm)were observed.The sex ratio significantly deviated in favor of males(1:0.90)(χ^(2)=1.99).However,there are significant differences between sexes over months in June(χ^(2)=10.89),July(χ^(2)=11.91),August(χ^(2)=6.10)and September(χ^(2)=4.41).The monthly variation of the gonadosomatic index(IG)peaked between February and April for males and females,indicating its spawning period.The interpretation between condition factor(K)and hepatosomatic index(IH)showed that the energy mobilization from the body assists the gonad maturation.The batch fecundity of 42 mature females ranged from 15.7 cm to 21.4 cm,and mass was 142.6 g-333.0 g giving 20,438 to 121,829 eggs.The length at first maturity of males and females were 12.45 cm and 15.78 cm,respectively.The male reached earlier maturity than the female.This study increases the understanding of reproductive aspects of C.coeruleopinnatus for future formulation of rules and regulations for suitable fishery management in Terengganu waters.