Morphological and parasitological variations of African lungfish, Protopterus annectens in dry and rainy seasons

Abstract

This study was carried out to determine the seasonal morphological and parasitological variations of African Lung fish (Protopterus annectens) from Upper River Benue, Nigeria. Twenty specimens each of the fish samples from the two seasons were collected monthly for a period of ten months and transported fresh (alive) to the Veterinary laboratory Teaching Hospital, University of Agriculture, Makurdi in plastic jars. The fish samples were identified and sorted into male and female. The total and standard lengths measurements were recorded while the weight was measured. Length weight relationship was determined. Examination for parasites on the fish samples was carried out. Parasitic indices (prevalence (%), and mean intensity, percentage parasite load and percentage frequency of occurrence of each parasite species per location in fish were calculated. The mean total length, total body weight and condition factor of Protopterus annectens in dry season were 36.25cm±0.67, 515.60g±25.90 and 0.91±0.023, respectively while in rainy season, the mean total length, total body weight and condition factor of 34.74cm±0.63, 460.60g±24.20 and 0.91±0.019, respectively. There was no significant difference (p > 0.05) between the mean total lengths, total body weight and condition factor of the fish sample in both seasons. Out of the 400 samples of P. annectens used for the study in dry and rainy seasons, 31.75% were infested with 242 different parasites. Of the total parasites, 50.83% parasites were recorded in dry season from 67.00% infested fish samples while 48.40% parasites were recorded from 32.00% infested fish. Of the parasites species, Contracaecum sp was the most prevalent (34.15%) in dry season. This parasite accounted for 18.70% in the intestine and 15.45% in the stomach while Eustrongyloids sp was the most prevalent (27.36%) in rainy season accounting for 22.64% in the intestine and 4.72% in the stomach. The least prevalent parasite load (3.25% in dry season and 2.83% in rainy season) was recorded for Trichodina sp. Among the body organs of the fish samples, intestine recorded the highest percentage parasite load (50.41%) in dry season while stomach had the highest percentage parasite load (49.06%) in rainy season. The least (3.25% in dry season and 2.83% in rainy season) were recorded for skin. Generally, intestine had the highest percentage parasite load (98.52%) with 50.41% in dry season and 48.11% in rainy season. Female P. annectens from both seasons had more percentage parasite loads (61.79% in dry season and 53.77% in rainy season) than the male P. annectens in both seasons (38.21% in dry season and 46.23% in rainy season). There were variations in percentage parasite load among the length and weight groups of the fish samples and conclusively, higher percentage parasite load (50.83%) was recorded in dry season than the rainy season (48.40%).

Keywords: Protopterus annectens, parasites, dry and rainy seasons and upper River Benue