scholarly journals Effect of some heavy metals on physiological and chemical parameters in Nile tilapia (Oreochromis niloticus L.)

Author(s):  
Nabil Abdel Hakim ◽  
Ahmad Helal ◽  
Mahmoud Salem ◽  
Ahmad Zaghloul ◽  
Mohamed Hanbal
2019 ◽  
Vol 8 (1) ◽  
Author(s):  
Nahid A.A. Siddig ◽  
Asma A. Ahmed ◽  
Sarra A.M. Saad ◽  
Faisal Hammad Mekky Koua

Municipal sewage sludge from wastewater treatment is an important nutritional source for sustainable agriculture. Here, we report on the assessment of the accumulation of heavy metals in Nile tilapia Oreochromis niloticus (Trewavas 1983) fed on earthworms Eisenia fetida reared on soil treated with different concentrations of sewage sludge (25% and 100%) during sludge-earthworm-fish short-term cycling. In this short-term cycling the Nile tilapia collected from the White Nile were chosen as final consumers, whereas the earthworms reared on loam soil mixed with different ratios of sludge were used as a feed for the final consumers. Our results indicate that the concentrations of Cd2+, Cr2+, Pb2+ and Zn2+ in the sludge treated soil are proportional to the sludge content in the soil. Importantly, the accumulation of these heavy metals was significantly low in the earthworms and the Nile tilapia in comparison with the treated soil and that these concentrations in the Nile tilapia were below the international limits recommended by the US Environmental Protection Agency (2014). Moreover, the growth and overall flesh quality of the fish were improved as indicated by the growth increase up to 146% when fed on earthworm reared in 100% sludge. Additionally, our physicochemical properties (i.e. pH, soil moisture, electric conductivity and organic matters) evaluation on the soil indicates an improvement of the soil quality when mixed with sewage sludge. These results suggest a sustainable application of sewage sludge in fish culture owing to its high nutritional values, low cost, and low risk of hazardous heavy metals when using primary consumers with heavy metals bioaccumulation capability such as E. fetida.


2020 ◽  
Vol 6 (3) ◽  
pp. 431-437
Author(s):  
Mohammad Ashaf Ud Doulah ◽  
SM Majharul Islam ◽  
Mohammad Shadiqur Rahman ◽  
Md Shariful Islam ◽  
Mohammad Harun Or Rashid ◽  
...  

The study was carried out to identify the parasite and causative diseases on cage reared tilapia at Bakerganj upazila, Barisal district. The infected tilapia fishes were collected from the cages and brought to the laboratory to find out signs, symptoms and infection area on the fish body. Physico-chemical parameters of water, such as water temperature, pH, dissolved oxygen, nitrate, phosphate and ammonia were monitored fortnightly. The values of water temperature (°C), pH, dissolved oxygen (mg/l), nitrate (mg/l), phosphate (mg/l) and ammonia (mg/l) were 32.4±2.1, 6.2±0.3, 7.52±0.4, 0.028±.008, 11.30±2.26 and 0.09±0.02, respectively but the concentration of nitrate was so higher during the study time. Eleven species of parasites namely, Chilodonella sp, Trichodiniasp., Gyrodactylussp.,Cichlidogyrus sp., Capillariasp, Orientocreadium sp, Eustrongylidae sp, Allocreadium sp, Euclinostomum sp, Tylodelphys sp. and Metagonimus spwere were identified. Parasites were found on all the examined parts of the fish body but gill showed the most infested area of the host. Highest mortality rate was occurred in the month of October and lowest mortality rate was in July. In this circumstance, proper management system and handling are best ways to prevent diseases and reduce the mortality rate of tilapia on cage farming in the southern area. Res. Agric., Livest. Fish.6(3): 431-437, December 2019


Author(s):  
Ong’eta M. K Wamboka ◽  
Syprine A. Otieno ◽  
Jemimah A. Simbauni

The Nile tilapia, Oreochromis niloticus, is a tropical fish species of commercial importance in both aquaculture and in the wild. It plays a great role in human nutrition and food security. River Ruiru is one of the rivers faced with pollution from nearby industries. It is inhabited by various species of fish such as tilapia and common carp, which, may be harvested by surrounding communities for food. High levels of heavy metals disrupt normal reproductive process in fish. Besides, it has been reported that edible fish contaminated with heavy metals has deleterious effects on the health of humans and other animals that consume them. There is no documented information on the association between heavy metals and the reproductive biology of Oreochromis niloticus in River Ruiru. This study was aimed at assessing the level of heavy metals in fish ovaries and their association with selected reproductive parameters in the reproductive cycle of O. niloticus. Fish samples were collected monthly, for 8 months, from the downstream and upstream sections. Gonadosomatic index (GSI), serum 17β-estradiol (E2) levels and levels of heavy metals lead, cadmium, copper, iron and zinc in ovaries were determined. The levels of the heavy metals were measured using Atomic Absorption Spectrophotometer. The level of E2 was analyzed using Enzyme-Linked Immunosorbent Assay. There was no significant difference in the GSI between the upstream and the downstream sites (t=0.82, p=0.416). Similarly, there was no significant difference in the levels of E2 between the downstream and the upstream sampling sections. In the downstream, the levels of lead and iron in fish ovaries were significantly higher compared to the upstream (lead: t = 3.36, p = 0.002; iron: t = 4.920, p=0.001). The results showed that levels of heavy metals did not associate with the selected reproductive parameters in the Nile tilapia, along River Ruiru. Levels of lead and cadmium were above allowable concentrations for fish consumption when compared to WHO levels. The study recommends that the Ministry of Environment and Natural Resources should put measures in place to stop discharging raw effluents into River Ruiru.


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