Iraqi Journal of Veterinary Sciences

According to their toxicity, toxic heavy metals such as arsenic, mercury, cadmium, copper, zinc, and lead are believed to be the most harmful to humans, fish, and the environment. Because their levels are rising due to human activities endangering aquatic species and people, the current study sought to ascertain the level of toxic heavy metals in five catfish parts (skin, liver, muscles, gills, and ovaries). In the northern part of the Shatt Al-Arab, catfish samples were collected in March 2022. ICP-MS was used to detect target metal levels. According to the results, arsenic accumulated in the skin and muscles at a rate of 0.22 and 0.21ppm, respectively. In contrast, the levels of arsenic in the various body parts are not statistically different. Additionally, cadmium showed no noticeable variances in the studied body parts. Furthermore, the liver had the most significant copper accumulation 18.72ppm. Furthermore, mercury accumulation in various body parts was shown to vary statistically, with the highest levels in muscles 0.66ppm. In addition, zinc was accumulated in the body parts in the following sequence: gills, ovaries, liver, skin, and muscles, respectively, while in the following sequence: muscles, skin, gills, liver, and ovaries respectively in the lead. Moreover, there were no statistically significant differences in the quantity of zirconium that accumulated. According to the current study, the catfish’s body parts did not accumulate toxic heavy metals at high rates. This may be due to study area the environment and the mechanisms of treating these types of metals by catfish. 

A total number of 400 Clarias gaiepinus were collected alive from several and various locations at El-Burullus Lake and Lake Nasser, to investigate the prevailing nematodes that infect this fish species from the two locations. Nearly all the examined fish were positive for one or more nematodes; four spp. of two families were identified from Clarias gaiepinus at El-Burullus Lake: Procamallanus laeviconchus, Paracamallanus cyathopharynx, Neocamallanus spp. (recovered from the gall bladder for the first time) and Terranova spp. larvae (recorded for the first time in Kafr El-Sheikh Governorate representing new locality record), one nematode from Clarias gaiepinus at Lake Nasser: 3^rd stage  larvae (L₃) of Contraceacum spp. (has zoonotic importance). The prevalence of Procamallanus laeviconchus, Paracamallanus cyathopharynx, Neocamallanus spp. and Terranova spp. larva were 37.5%, 44%, 0.5% and 10% respectively, meanwhile the prevalence of L₃ larvae of Contraceacum spp. were 100%. This study was planned to compare between the nematodes infecting Clarias gaiepinus from the two lakes evaluating clinical signs, postmortem examinations, parasitological examinations, seasonal prevalence and histopathological investigations of infected fish with different nematodes infestation. Clarias  gaiepinus must be eviscerated as soon as possible after catching to prevent 3^rd stage larvae of Contraceacum spp. in the abdominal cavity from liberating from their sheaths and attacking the fish musculature (the edible part in the fish) as well as,prevent Terranova spp. larvae in the gills from attacking another parts of the fish and thus prevent the transmission of the nematodes of zoonotic importance to the consumers.

Bacteria pathogens may cause a serious loss in aquaculture and also health hazards to humans. On the basis of biochemical characteristics and API-20E system, all isolates of pathogens from diseased fish were identified as Aeromonas spp, the most predominant bacterial species were A. sobria 46.7%, A. caviae 19.03%, A. jandaei 8.6 % and A. veronii 8.6 %. One hundred and twenty Nile catfish Clarias gariepinus were divided into four equal groups (1,2,3 and 4) were challenged with Aeromonas sobria which predominant isolates, Gp. (1) was challenged only, while Gps. (2, 3 and 4) were treated after challenged with ciprofloxacin, clove extract and ciprofloxacin and clove extract in combination, respectively. The antibacterial activity of antibiotic and clove extract in their therapeutic doses decrease the mortality rate as (20, 16 and 13%) respectively compared with non-medicated Gp. (1) which recorded mortality 83%. Internal signs of infection with Aeromonas sobria in African catfish (Clarias gariepinus) include congestion of the hepatic blood vessels, areas of coagulative necrosis in the liver and hydropic degeneration of renal tubules according to the histopathological examination. In-vivo the combination of ciprofloxacin and clove extract was the choice as alternative bacterial therapeutic agent in infected Clarias gariepinus with Aeromonas sobria. Moreover histopathological changes have been widely used as biomarkers in the evaluation of the health of fish exposed to contaminants.