Prevalence and intensity of helminth parasites in the snake headed fish, Channa punctatus of Savar, Dhaka

Ten species of helminth parasites i.e. Neopecoelina saharanpuriensis, Mesolecitha linearis, Asymphylodora tincae, Genarchopsis bangladensis, Ditestolepis diphana, Senga sp., Neoechinorhynchus tylosuri, Pallisentis sp., Ascardia larvae., Gnathostoma spinigerum were identified from Channa punctatus of Savar area. Majority of the parasites were found in the intestine. The overall prevalence of infection of the parasites was 32.5% and the mean intensity was 1.46±1.29. Both the prevalence (34.61%) and mean intensity (1.5±1.21) were higher in male fishes than the female fishes (28.57% and 1.375± 0.99 respectively). The prevalence (13.75%) and mean intensity (1.64± 0.67) of trematodes were the highest among the parasites groups. Both the prevalence and mean intensity were the highest in the intermediate length (10.1-15.1cm) and weight (21-31gm) groups of fishes.


INTRODUCTION
Parasites occupy definite position in the animal kingdom for their remarkable adaptations and damaging activities to the host.The importance of parasite is related directly to the fish that may affect the general public health (Hoffman, 1967).Every parasite living in or on a fish extents some degree of harmful influence on its host.The normal growth of fish is interrupted or inhibited if they are heavily infected with parasites.The composition of the parasites of fish depends on various environmental factors such as physico-chemical factors of the water, geographical location of the habitat, season of the year, the fauna present in and around the habitat etc. Cheng (1973) stated that the irritating activities and damages of host's tissue lining, the walls of intestine, stomach, bile duct, liver etc. by the parasites, causes microscopic lesions in the host tissue which become the site for secondary infection by the bacteria.Frequency of infestation and distribution of parasites within different organs of fishes are influenced by age and diet, abundance of parasites within the fish and their abundance (Rahman & Parween, 2001).
According to Gupta (1983), injury of fishes can carry heavy infection of parasites that cause deterioration in the food of fish and may even result in their mortality.Besides, there are a number of helminth parasites which are transmitted to man only through fishes.The similarity in parasitic fauna between species utilizing similar food was also noted (Dogiel, 1964).The difference in feeding habits has considerable impact on intestinal parasites, but related species living together are likely to share a similar array of ectoparasites inspite of their differences.
Parasitic infestation has harmful influence on fish health that inhibits the normal growth of the hosts and may outbreaks high mortalities.The declination of Channa punctatus is regarded as its susceptibility to Epizootic Ulcerative Syndrome disease (Harris et al., 1992) and over exploitation and habitat degradation (Hussain, 2010).Studies on the Channa punctatus have so for been done mainly on the breeding program of this fish ( Srivastava & Singh, 1994) and histopathology of diseased fish (Chandra, 1998;Afroz et al., 1999).Infestation of helminth parasites and histopathological changes in snake headed fishes was reported by Chowdhury, 1992.The morphology of Genarchopsis dasus parasites infesting Channa punctatus was described by (Banerjee, 1992) and seven parasitic species as well as Genorchopsis bangladeshensis of Channa punctatus was identified in Bangladesh where fishes were collected from hatchery and sewage lagoon (Alam et al., 2010 ).
Study of parasites of this fish is scanty in Bangladesh though several attempts have been taken to explore the parasitic fauna of fishes of this country (Rahman, 1989;Khan, 1985;Ahmed & Rouf, 1981).Thus the main purpose of the present study was determined to assess the prevalence and intensity of helminth parasites of Channa punctatus collected from Savar area, Bangladesh.

MATERIALS AND METHODS
A total of 80 fish samples Channa punctatus were collected from different fish markets in Savar, Dhaka at regular interval from January, 2013 to August, 2013.Host fishes were brought to the laboratory of Zoology Department, Jahangirnagar University for detailed investigations.Sexes of the hosts were identified according to body color, bulged-out bellies, genital pore and internal gonad.The total length of host fishes were measured by using centimeter scale and divided into three length groups (viz.: 5-10cm, 10.1-15.1 cm, 15.2-20.2cm).For the collection of helminth parasites the organs like body cavity, liver, stomach, intestine etc. were separated and examined under steroscopic Olympus dissecting microscope.The collected parasites were first washed in physiological saline solution and thereafter were fixed in alcohol-formaline-acetic acid (AFA), stained in borax-carmine and cleared in lectophenol (Cable, 1977).The parasites were identified according to Yamaguti (1958Yamaguti ( , 1963)).Finally, the prevalence and mean intensity of helmith parasite of each species identified were calculated after Margolis et al. (1982).Statistical data were analysed by means±SDs of five replications and by using SPSS 11.5.
The prevalence of infestation was 32.5% and the mean intensity of infestation was 1.46 ±1.29.The prevalence of infestation in male and female hosts was 34.61% and 28.57% respectively (Table 1).The mean intensity was slightly higher in males (1.5±1.21)than in females (1.375±0.99).The present study revealed that both the prevalence and intensity were highest in male than in female (Table 1).It was revealed that male hosts were observed to be more infected than females.Akther (1995) also showed the same result in Anabas testudineus.According to Aloo et al. (2004), the main reason for the differences in parasitic load with sex is physiological.In the present study, it was found that the prevalence and intensity of parasites of different groups varied for sex of hosts.The prevalence of trematodes, cestodes, acanthocephalans and nematodes in Channa punctatus were 13.75%, 6.25%, 3.75%, 8.75% and their mean intensities were 1.64±0.67,1.6±0.55,1.0±0.00 and 1.28±0.49.The highest prevalence (13.75%) and intensity (1.64±0.67)were observed in trematodes.
The prevalence of Neopecoelina saharanpuriensis, Mesolecitha linearis, Asymphylodora tincae, Genarchopsis bangladensis were 3.75, 2.5, 2.5 and 05% respectively, and their mean intensities were 1.66±0.58,1.5±0.71,1.5±0.71and 1.75±0.71respectively.The prevalence of Ditestolepis diphana, Sengasp.,Neoechinorhynchustylosuri, Pallisentis sp.,Ascardia sp., Gnathostoma spinigerum were 2.5, 3.75, 1.25, 2.5, 6.25 and 2.5% respectively and their intensities were 1.5±1.12,1.66±1.12,01±0.71,01±0.00,1.2±1.41 and 1.5±2.12respectively(Table 2).N. saharanpurensios was also found in the study of Basirullah (1973) and Chowdhury (1992) in C. punctatus.The trematode parasites Gnathostoma spinigerum was previously recorded from Nandus nandus by Nahida (1993) and Khanum (1997) in Bangladesh.Rahman & Parween (2001) reported that seven species of helminth parasites from C. punctatus which disagree the present findings.It has been noticed that the parasites show distinct relation with the season.The present investigation was carried out for eight months not covering all the season year round.Perhaps this is one of the causes of getting new parasitic fauna than the previous investigation.The parasites were found in stomach, gill, body cavity and intestine.Out of 38 parasites, 06 (15.79%) were found in the stomach, 04 (10.53%) were found in the gill, 07 (18.42%) were found in the body cavity and 21 (55.26%) were found in the intestine.The highest prevalence and intensity of parasites were observed in the intestine (Table 3).Ascaridia larvae remained free in the intestine.This observation was supported by Huq et al. (1983) who found this worm in the digestive tract of C. punctatus.The present investigation recovered the occurrences of Gnathostoma spinigerum inhabit in the intestine of examined host.Akther et al. (1997) and Nahida et al. (1994) also showed that the parasite infestation is higher in the intestine.Sarma (2012) also found the similar result during his study in three murrel host species.Khanum et al. (2011) also observed the maximum helminth infestation from intestine.Intestinal parasites inhabit the digestive activity of the host and indirectly inhabit vitamin and blood sugar metabolism and growth; parasites in the liver affect glycogen metabolism and growth (Rhode, 1993).
Both the prevalence (45.23%) and mean intensity (1.52) were the highest in the intermediate length group (10.1-15.1cm).The prevalence in small length group (5-10 cm) was 25% and in the largest length group (15.2-20.2cm) it was 16.66%.And the mean intensity was 01 in the small length group (10.1-15.1cm)and 1.4 in the large length group (15.2-20.2cm) (Table 4).Both the prevalence (42.55%) and mean intensity (1.5) were the highest in the intermediate weight group (21-31gm).Prevalence and intensity were 33.33% and 01 respectively in the lowest weight group (10-20gm) and 14.81% and 1.5 in the largest weight group (32-42gm) respectively (Table 4).One major reason is that as the fish grows, the amount of food it consumes, which includes the larval stages of the parasites increases (Paling, 1965;Meshego, 1989;Davey & Gee, 1976).According to Khanum & Parveen (1997), parasite infestation usually followed a direct relationship with length of Macrognathus acculeatus and Mastacemelus armatus.They also mentioned that prevalence and intensity were comparatively higher in larger and intermediate size-group of fishes respectively.Rahman & Parween (2001) reported maximum prevalence and mean intensity in intermediate size and smallest size group respectively in Heteropneustes fossilis, Channa punctatus and Colisa fasciatus.This later findings were also similar with the present findings.Nahar (1988) reported that the intermediate size group was more infected by the parasites than the smaller and larger size groups.It is also well known that the host age and the habitat of the host plays vital role in the differences of prevalence.Biology of parasites, intermediate hosts, host behavior and most vitally seasons probably have great effects on infestation of parasites on host.So, further investigation with large number of hosts from all over Bangladesh considering seasonal variation and other biological attributes may provide a complete record of the parasites of Channa punctatus.