Redbelly Tilapia Research Articles

Occurrence of Ectoparasites on Tilapia zillii (Red Belly Tilapia) Gervais 1848 in The Tono Reservoir, Navrongo, Ghana

This study was carried out to assess the occurrence of endoparasites in (Tilapia zillii (Gervais, 1848)) from Tono reservoir, Navrongo Ghana. A total of 120 fish samples were collected from the upstream, midstream and downstream regions of the reservoir using cast nets. All the collected fish samples were transported to the research laboratory in the University for Development Studies and examined for ectoparasites during January 2022 to August 2022. Five ectoparasites namely Trichodina sp. of Protozoans ciliates, Dactyolgyrus sp. of Monogenean, Argulus sp. and Lernaea sp. of Crustaceans and the Diplostomum sp were identified. Overall prevalence of the fish parasites was 52.32 %. Intensity of the parasites observed ranged between 1.58% to 3.52%. Highest prevalence 70 % was reported in dry season while lowest (31.67%) was reported in the rainy season. Female fish samples had higher prevalence (64.47 %) than males (27.27 %). Fishes of downstream had highest prevalence (92.5 %) than upstream (17.5 %). Fish samples with maximum length and weight were highly (65.15 %) infected than small sized fish with low body length and weight (33.33 %). It is debatable if the degree of ectoparasite activity found in this study will constitute a serious danger to the local fish population. Yet, in order to stop disease outbreaks brought on by an increase in ectoparasites, the reservoir must be given significant attention by using optimum management strategies. This study shows that dry season affects the fish business and result in poor quality fish meat with risk of diseases infection.

Hazard Identification and Potential Risk Analysis of Toxic Metals in Redbelly Tilapia (Coptodon zillii) Consumed and Surface Water from the Niger Delta Estuary

Anthropogenic activities have caused toxic metals to escalate, polluting rivers, and accumulating in water, sediments, and fish. This harms aquatic ecosystems and has enduring impacts on humans and aquatic life. The study aimed to assess the accumulation of heavy metals (Pb, Cr, Cu, Fe, Ni, Cd, and Zn) in Redbelly tilapia (Coptodon zillii) and water obtained from three sampling stations along Atuka Creek which is a crude oil-contaminated site in a southern creek in Nigeria. The investigation further intends to evaluate potential health risks linked to the consumption of C. zillii and to analyze the pollution and productivity levels of the corresponding aquatic ecosystem. The results show significant variations in heavy metal concentrations across stations, with Station 1 exhibiting the highest contamination levels attributed to its proximity to pollution sources. The fish from Station 1 revealed elevated levels of contamination, surpassing recommended limits for Pb, Fe, Ni, and Zn. Calculations of chronic daily intake (CDI) values indicate potential health risks for both adults and children, particularly in Stations 1 and 2. The hazard quotient (HQ) and hazard index (HI) values surpassed safe limits in these stations, suggesting non-carcinogenic health risks linked to fish consumption and swimming. Moreover, lifetime cancer risk (ILCR and TLCR) assessments revealed an augmented risk of cancer, especially in Stations 1 and 2. These findings emphasize the need for stern pollution control measures, regulations, and remediation strategies to mitigate heavy metal contamination, ensure water quality, and safeguard public health in southern Nigerian communities.

PREVALENCE OF ECTOPARASITES OF FRY TILAPIA (COPTODON ZILLII) FISHES FROM EUPHRATES RIVER, IRAQ

Ectoparasitic infection represents one of the main challenges to freshwater and marine fish in all areas of the world. This study detected ectoparasite types in Fry Redbelly Tilapia Fishes. The specimens (250) were purchased from a market with a source of fish from the Euphrates River. Fishes were collected from December 2022 until the end of April 2023. The samples were used for macroscopic inspection, gross viscera, and microscopic exam - wet mount of fins, skin, gills and eyes. Ectoparasite species were obtained on fins, skin, and gills, and the eyes had no infection. The total prevalence was 140 (56%) of 250 fish. Significant fish types with weight and length are at (P ≤ 0.05) and (P ≤0.01), respectively. The mean and standard deviation according to weight were 71.4 and 14.7, while according to length, they were 15.6 and 1.9. Non-significant for genders in both types at (P ≥ 0.05). The host Coptodon zillii is infested by four types of ectoparasites were included, with prevalence for each one being Ichthyophthirius sp., 80/250 (32%); Trichodina sp., 30/140 (12%); Dactylogyrus sp., 20/250 (8%); Gyrodactylus sp.10/250 (4%). In conclusion, all parasites, namely single-host types. Management measures should be taken to save the procurement and import from reputable global markets.

Prevalence of Endoparasites and Haematology in Redbelly Tilapia from a Shallow Tropical Reservoir in Ghana

The goal of this study was to assess common endoparasites on Tilapia zillii in the Tono Reservoir, as well as to investigate the mean intensity and prevalence of these parasites. A total of 175 fish specimens were examined during the study. Endoparasites of three metazoans and one protozoan were observed from the Tilapia zillii gills, intestines, and stomach. The findings showed that the most common endoparasites affecting Tilapia zillii are Ichthyopthirius multifiliis, Bothriocephalus sp., Contracaecum sp., and Dactylogyrus sp. Also, Contracaecum sp had the highest prevalence of 29.71, followed by Bothriocephalus sp (18.86), Ichthyopthirius multifiliis (12), and Dactylogyrus sp (6.86). The average quantity of Bothriocephalus sp was 0.84, Contracaecum sp was 1.33, Dactylogyrus sp was 0.31, and Ichthyopthirius multifiliis was 0.54. The reservoir's physicochemical parameters changed every month due to inflows and other runoffs joining. Low levels of these parameters were discovered to influence the prevalence and distribution of these parasites. Haematological parameters showed significant changes between the adult and fingerling groups, where it was observed an improvement in health status in the adult group. It was also observed that fingerlings (0.1–20 g) were more infected, which significantly affected their blood profile.
 Keywords: Tilapia zillii, endoparasite, blood profile, pathogenic effects, environmental stress

Aspects of the biology and population structure of Oreochromis niloticus, Coptodon zillii and Oreochromis leucostictus tilapia in Lake Naivasha, Kenya

AbstractThe Nile tilapia (Oreochromis niloticus), Redbelly tilapia (Coptodon zillii) and Blue spotted tilapia (Oreochromis leucostictus) were introduced into Lake Naivasha in the 1950s to diversify and boost the lake fisheries. These species have since been exploited in the commercial gillnet fishery. The fish stocks, however, are currently facing problems of pollution, wetland degradation and intense fishing pressures. Accordingly, the present study investigated some aspects of the biology and population structure of the three tilapiine species in light of changing lake conditions. Fish samples were collected from January to December 2019 using multifilament gillnets of 2.0‐to‐6.0‐inch mesh sizes. Immediately after their capture, the fish specimens were transported to the lab for morphometric measurements and analysis of maturity. The highest and lowest mean (±SD) total length (TL) were exhibited by O. niloticus (22.9 ± 5.2 cm) and C. zillii (14.5 ± 2.1 cm), respectively. Similarly, O. niloticus exhibited a higher mean weight (268.4 ± 18.0 g) and body depth (7.6 ± 2.5 cm), compared to the other species. O. niloticus exhibited an isometric growth pattern, while C. zillii and O. leucostictus exhibited negative allometric growth. The fish species were in good condition, with mean condition factors of 1.59 ± 0.07, 1.51 ± 0.06 and 1.23 ± 0.03 for C. zillii, O. leucostictus and O. niloticus, respectively. Furthermore, the condition factors for O. leucostictus and O. niloticus varied by size class, exhibiting a decreasing trend with increased fish size. The male:female sex ratio revealed significantly more males than females for O. niloticus (2.30:1.0) and O. leucostictus (2.36:1.0), although not for C. zillii (1.15:1.0). O. niloticus (28.0–29.0 cm TL) matured at a larger size, followed by O. leucostictus (21.0–26.0 cm TL), and C. zillii (15.0–17.0 cm TL). In comparison, values of length‐weight parameters, condition factor, sex ratio and size at first maturity of the studied fishes varied in Lake Naivasha, Victoria, Albert and George. The gillnet mesh ≤3.0″ mainly targeted small‐sized immature fish, while mesh ≥4″ targeted mature fish, particularly O. niloticus. It was concluded that gillnets with ≥4.0″ mesh could safely be applied for this fishery in Lake Naivasha, whereas the use of smaller mesh should be controlled to protect the juveniles as a means of maintaining sustainable fisheries. Furthermore, the present study also provided useful information, including size at maturity that is vital for setting mesh size for managing the lake fishery.

Estimation of the gill respiratory surface area and some features of the red muscle fibers in two teleost species

The current study is a comparative analysis of the Gill Respiratory Surface Area (GRSA) and some features of the red muscle fibers including the proportions and diameters of the red muscle fibers in three body regions in two teleosts species; torpedo scad, Megalspis cordyla (L.) which belongs to the carangid and the red belly tilapia, Cotodon zillii (Gervaias, 1848) which belongs to cichlids. Fifty fishes (25 fishes for each species) were used in the current investigation. They range in length from 100 to 300 mm and their weight ranged between 66 and 305 gm. The results show that the M. cordyla have GRSA ranged between 78 and 100 mm2/gm whereas it ranged between 56 and 146 mm²/gm in C. zillii. The fish weight was the influential factor on the values of the relative GRSA (mm²/gm) while the total length of gill filaments was the influential factor on the values of the total GRSA (mm²) of the studied fishes which showed significant differences (p<0.05) between the studied species. The difference in the proportions of the red muscle fibers among the three body regions of both species showed a significant difference (P<0.05) between the total length of the fish and the proportions of the red muscle fibers which ranged between 8.16 and 12.80 % in M. cordyla whereas it was between 5.42 and 9.24 % in C. zillii. Also the results presented an increase in the proportions of the red muscle fibers towards the posterior region (R3) which were 8.80-12.80 % in M. cordyla while they were 6.24-9.24 % in C. zillii. The results revealed that the approximate diameters of the red muscle fibers varied between 13.70 and 47.85 μm in M. cordyla while they ranged between 17.10 and 44.50 μm in C .zillii but were not statistically significant differences (P>0.05) between the two species.

Substratum preferences of juvenile Red belly Tilapia (Coptodon zilli, Gervais, 1848)

Substratum preferences of the young of Alien fish species known as Red belly Tilapia locally known Bultee (Coptodon zilli, Gervais, 1848) [1] with 30–40 mm TL were studied in the laboratory. The work tested the hypothesis that fishes vary in habitat preference and that they make use of the differences in substrates’ types within the water body in nature. Substratum preference for juvenile of C.zilli was calculated by the calculations of individuals noticed inside precise habitat kinds.The fish species demonstrated significant changes in their substrate choices. Muddy sand appears to be usually more appropriate settlement ground for juvenile of this fish. Pebble, Gravel, Sand and Mud were less favorable. Plastic floor was unfavorable and the fish would generally settle in the other substrates preference to it. This work proposed that the particle size of the substrate influences settlement preference of the fish.

Morphometric, Meristic and Conditional Factor Characterization of Redbelly Tilapia (Coptodon zillii) in Lake Komadugu, Yobe State, Nigeria

This research was carried out to study the morphological characteristics of Coptodon zillii from Lake Komadugu in Yobe State, Nigeria using morphometric measurements, meristic counts and length-weight relationship. A total of 60 specimens of Coptodon zillii were purchased from the fisher folks at landing site in Lake Komadugu, examined and analyzed for morphometric and meristic characterization. The results revealed that all the morphometric characters of C. zillii in Lake Komadugu varied whereas some meristic characters including mean number of rays on pectoral fin (8.00 ± 0.00), pelvic fin ray (5.00 ± 0.00), anal fin spine (3.00 ± 0.00), pelvic fin spine (1.00 ± 0.00) and number of lateral line (2.00 ± 0.00) were constant. A significant linear relationship was established and represented by the equation: W =0.008SL2.097 (r =0.6410 d.f. = 58) for male, W =0.001SL3.013 (r = 0.9600 d.f. = 58) for female. Mean condition factor which was not significantly different (p>0.05) showed that male C. zillii had 1.80 ± 0.27, female (1.92± 0.26) and pooled sex (1.86 ± 0.25). Findings of this study implies that C. zillii from Lake Komadugu are in good health. In conclusion, these findings are very useful in stock assessment, population dynamics, sustainable management and conservative measures of C. zillii in Lake Komadugu.

A Composition and Abundance of Alien Fish Species in Inland Waters, Southern Iraq

Alien fish species have negative effects on the abundance, diversity and richness of native fish species in southern Iraq. The numbers of alien fish species are constantly increasing due to the entry of invasive species. This has resulted in shifts in the historical composition of fish community structure and scarcity of some native species which represent the keystone in the building of fish populations.
 Fish samples were monthly collected from three sites in southern Iraq (Al-Chibyaish marsh, the lower parts of Euphrates River, and the northern part of Shatt Al-Arab River) from April 2017 to June 2018. A total of 14,853 individuals of fish were sampled, which represented 26 species, 24 genera and 13 families of bony fishes. Ten alien fish species were recorded, affiliated to nine genera and five families, namely Cichlidae, Cyprinidae, Heteropneustidae, Poeciliidae and Xenocyprididae. Three alien fish species dominated the abundance in the three sites; the Prussian carp Carassuis gibelio comprised 12.58%, 26.19%, and 13.84%, the Blue tilapia Oreochromis aureus formed 16.78%, 13.66%, and 18.79%, , and the Redbelly tilapia Coptodon zillii comprised 7.37%, 7.71%, and 14.66% of the total number of species in three study sites respectively. ( …. )
 These alien fish species created serious shifting in fish composition, diversity, richness, and abundance of native fish populations in comparison to the results of the historical survey in southern Iraq.

Ecology of the Critically Endangered Singidia Tilapia (Teleostei: Cichlidae: Oreochromis esculentus) of lake Kayanja, Uganda and its conservation implications

Singidia Tilapia Oreochromis esculentus is a Critically Endangered native tilapia fish species endemic to lakes Victoria and Kyoga basins of East Africa, however, it disappeared from these main lakes due to overfishing, environmental degradation and predation by the introduced Nile Perch Lates niloticus. Remnant populations of this fish species is now restricted to satellite lakes including Lake Kayanja of the Victoria basin. This study provides updated information about the population abundance, critical habitat, threats and diet of Singidia Tilapia to inform conservation decisions to revive its populations in the wild. Fish data collection and mapping of nursery and breeding habitats of Singidia Tilapia on Lake Kayanja was conducted between February 2016 and October 2017. In all the areas mapped and sampled, Singidia Tilapia (with a size range of 11–27 cm TL) was the most abundant (43%) relative to exotic Nile Tilapia Oreochromis niloticus (21%) and Redbelly Tilapia Coptodon zillii (36%). The emergence of introduced (exotic) tilapias like Nile Tilapia recorded in this study could be attributed to cage fish farming being carried out in this Lake. The diet of Oreochromis esculentus consisted mainly of detritus (60.8 %), plant materials (27.7%) and blue-green algae (5.5%). Destruction of critical habitats and presence of introduced fish species were noted as the major threats to this fish and its habitats. The generated information could contribute to guiding stakeholders to undertake appropriate actions to conserve this threatened fish species and its habitats.

PRELIMINARY STUDIES ON RED BELLY TILAPIA COPTODON ZILLII CAUGHT FROM OYAN DAM, OGUN STATE, NIGERIA

The study was carried out on the biological aspect of Redbelly Tilapia, Coptodon zillii collected from Oyan Lake, Abeokuta North Local Government Area, Ogun State, Nigeria, with the aim of contributing to the baseline data for carrying out further studies on its ecology, conservation and development. A total of two hundred and fifty four fish (254) specimens were caught from the Ibaro landing site of the Lake between March and July, 2015. The total length (cm), standard length (cm), head length (cm), body width (cm), body depth (cm), snout length (cm), eye diameter (cm) and body weight (g) were measured. The stomach content was also assessed in order to determine its food and feeding habit. The mean total-length, standard-length, head-length, eye-diameter, snout-length, body-depth, body-width and body-weight during the study were 10.98±0.61cm, 8.56±0.14cm, 2.5±0.08cm, 3.67±0.15cm, 1.52±0.11cm,1.37±0.17cm, 4.05±0.07cm, 34.25±3.02g respectively and their ranges were (4.5-18.7cm), (3.2-15.2cm), (1.1-5.8cm), (2.0-6.8cm), (0.8-3.0cm), (1.1-4.8cm), (1.4-7.3cm) and (6.0-132.0g). A negative allometric (b<3) growth pattern was observed for the stock. The meristic characteristics of C. zillii were (DFR) XIV 10 – XVI 14; PVR, AFR III 8 –III 9; PFR 10 – 13 respectively. Stomach analysis showed that diatoms were the most abundant food items in the diet of C. zillii numerically, 29.98%, while desmids were the most abundant food items in terms of frequency occurrence, 27.82%. This study concluded that C. zillii is not morphometrically and meristically different from the already classified from previous studies. Also, C. zillii thrives well on available plants and detritus.
 

Description of a new species of Dermoergasilus Ho & Do, 1982 (Copepoda: Ergasilidae) from the redbelly tilapia Coptodon zillii (Gervais) (Perciformes: Cichlidae) in Basrah, southern Iraq

A new species of Dermoergasilus Ho & Do, 1982 (Copepoda: Ergasilidae) parasitic on the gills of the redbelly tilapia Coptodon zillii (Gervais) from Basrah, southern Iraq, is described. Dermoergasilus cichlidus n. sp. is morphologically similar to D. longiabdominalis El-Rashidy & Boxshall, 2001 in the body length to width ratio, the swimming legs armature, the shape of the urosome and the small slightly spiniform seta on the exopodal segment of leg 5. However, the main differences are the presence of long setae on the endopod of leg 1 in D. cichlidus n. sp. (vs relatively short setae); the inner apical spine on the tip of the endopod of leg 1 being only slightly longer than the outer apical spine (vs inner apical spine about twice as long as the outer); the first interpodal sternite ornamented with spinules (vs interpodal sternites not ornamented); and the caudal rami and anal somite of equal length (vs caudal rami length c.2/3 of the length of the anal somite). Dermoergasilus occidentalis can be distinguished from D. cichlidus n. sp. by the relative length of the antennal segments, the absence of a minute terminal spine on the digital process of the caudal ramus and by differences in the mouth parts.

Chemical and Microbial Quality Assessments of Some Economic Important Artisanal Fresh Water Fish Species (Tilapia zilli, Clarias gariepinus, Chrysichthys nigrodigitatus and S. melanotheron) in Selected Coastal Markets of Lagos State, Nigeria)

Nutritional qualities of some selected fresh water fish species sold for consumption in the Badagry, Epe, Ikorodu and Ojo areas of Lagos state, Nigeria was assessed to ascertain the wholesomeness and health risk associated with consuming the most common sort after fish in these locations. A total of 100 fish samples, Red belly Tilapia (T. zilli), African Mud Catfish (C. gariepinus), Silver Catfish (C. nigrodigitatus) and Black Chin Tilapia (S. melanotheron) (25 specimens each) with a weight ranges between 50-180 g, were collected from different locations. The samples were iced and taken to the Biochemistry and Pharmaceutical laboratory sections of the College of Medicine University of Lagos, Idi-Araba, Lagos, Nigeria. The iced samples were maintained in alternate layers of ice until spoilage was noticed. Chemical analysis was conducted using Spectrophotometer, Atomic Absorption Spectrophotometer, Sohxlet Extraction Apparatus, Thiobarbituric Acid (TBA), The Acid Value (AV), Peroxide Value (PV), Iodine value, Free Fatty Acids (FFA) and Saponification value were determined. The result indicates higher TBA (8.79 ± 0.05), (7.59 ± 0.06), (7.46 ± 0.04) and (6.99 ± 0.05) for T. zilli, C. nigrodigitatus, S. melanotheron and C. gariepinus respectively in Ojo Lagoon, higher iodine value (9.69 ± 0.01) for T. zilli in Ojo Lagoon; (8.75 ± 0.21), (9.35 ± 0.07) and (8.45 ± 0.07) for C. nigrodigitatus, S. melanotheron and C. gariepinus respectively in Epe Lagoon and the acid values (3.31 ± 0.04), (2.45 ± 0.04) and (3.79 ± 0.04) for T. zilli, C. nigrodigitatus and S. melanotheron respectively in Badagry Lagoon and (2.25 ± 0.04) in Ojo Lagoon were within the standard limits. Higher mean mould load recorded were (1.22×104), (1.78×103), (1.90×103) for C. gariepinus, S. melanotheron and T. zilli respectively in Ikorodu Lagoon, while (3.47×103) was recorded for C. nigrodigitatus in Badagry Lagoon. The results indicated a notable quality improvement leading to a high quality fish in terms of the taste, colour, odour, shelf life and market value. The high iodine value recorded in this study from different locations suggests that the fish species contain high level of unsaturated oil and as such could reduce the risk of heart diseases, high cholesterol, depression, anxiety, low immunity, cancer, eye disorders and ulcers in humans when consumed. None of the fish samples exceeded the mould load limit for fish thereby exhibiting no risk on public health; therefore the fish are wholesome and safe for human consumption.

Food Habits and Diet Relationship in the Redbelly Tilapia (Tilapia zillii) and Guenther’s Mouthbrooder (Chromidotilapia guntheri) from an Abandoned Gold Mine Reservoir, Southwestern Nigeria

The food and feeding habits of the redbelly Tilapia (Tilapia zillii) and Guenther’s mouthbrooder (Chromidotilapia guntheri) were investigated in an abandoned gold mine reservoir at Igun from June 2013 to May 2014. Using a cast net and gill-net fishing gears, 370 fish individuals were caught and their stomach contents were analysed by using the frequency of occurrence and numerical methods. Tilapia zillii comprised 53.78% (199 individuals), while Chromidotilapia guntheri covered up the remaining percentage (46.22%) which is made up of 171 individuals. Food items in the stomachs of T. zillii individuals predominantly consisted of detritus, mud and algae (77.97%), while those in C. guntheri individuals mostly consisted fish remains, detritus and algae (81.67%). T. zillii exploited more food items (23 of 27) as compared to C. guntheri (17 of 27). The Schoener’s index value for the species was 0.65. The study showed that T. zillii and C. guntheri exhibited benthopelagic exploitation and are mainly herbivorous and omnivorous respectively based on the food items observed in the stomach contents of these species. The fish species fed on related food items as confirmed by Schoener’s overlap index (0.65), suggesting that there was overlap in the dietary requirements of the two species. This index value, however, was probably not an indication of competition for food between these two species because they exploited abundant food sources.

Assessing the Influence of Tilapia on Sport Fish Species in North Carolina Reservoirs

AbstractRedbelly Tilapia Tilapia zilli and Blue Tilapia Oreochromus aureus are indigenous to Africa and the Middle East, but now occur throughout the southeastern United States. It is fairly well understood that foraging flexibility and wide salinity, oxygen, and temperature tolerances have led to general invasion success for most tilapia species. Conflicting empirical information about the influence of tilapia on native sport fish species, however, leaves natural resource managers unable to anticipate and prevent further introductions and potential associated risks to native sport fishes. This investigation focused on two North Carolina reservoirs with tilapia populations: Hyco Lake, a large reservoir in northcentral North Carolina and Lake Julian, a small impoundment in western North Carolina. These reservoirs receive heated effluent from power generation, which is assumed to provide winter refuge for tilapia at a time when temperatures would otherwise lead to mortality. We assessed relative abundances of the tilapias and native sport species (Bluegill Lepomis macrochirus, black basses Micropterus spp., and Black Crappie Pomoxis nigromaculatus) in these systems and examined their trophic interactions via diet and stable isotope analyses in both lakes. In Hyco Lake we assessed potential spatial interactions and influences on relative abundance using a priori candidate models and model selection via Akaike's information criterion (AIC). These analyses indicated little evidence of tilapias influencing the relative abundances of the sport species in Hyco Lake. In both lakes, however, we did find substantial diet overlap between the tilapias and Bluegill along with isotopic niche overlap between Blue Tilapia and Bluegill in Lake Julian and Redbelly Tilapia and Bluegill in Hyco Lake. Due to the omnivorous and flexible diet of all three species these interactions were not surprising, but the ultimate influence on Bluegill growth and size structure is unknown. Overall, our results suggest that tilapia are exploiting trophic niches that are not used by the sport fishes of interest in these two very different reservoir systems and that their direct impact on sport species is not substantial.

Fish as bioindicators for trace element pollution from two contrasting lakes in the Eastern Rift Valley, Kenya: spatial and temporal aspects

Lake Turkana and Lake Naivasha are two freshwater lakes in the Kenyan Rift Valley that differ significantly in water chemistry and anthropogenic influence: Lake Turkana is believed to be rather pristine and unpolluted, but a previous study has shown rather high levels of Li, Zn, and Cd in the migratory fish species Hydrocynus forskahlii, questioning this pristine status. Lake Naivasha is heavily influenced by agricultural activity in its catchment area and by direct water use, and high levels of metal pollutants have been reported in fish. This study presents the distribution of nine important trace elements in liver and muscle of the nonmigratory red belly tilapia Tilapia zillii from Lake Turkana and from Lake Naivasha (before and after a significant rise in water level due to as yet not fully understood reasons). In addition, trace element levels in the common carp Cyprinus carpio from Lake Naivasha are presented. Metal concentrations measured in the liver and muscle of T. zillii collected in Lake Turkana confirm the pristine status of the study site, but contrast with the results obtained for the migratory H. forskahlii. Comparing T. zillii from the two lakes reveals a clear difference in accumulation patterns between essential and nonessential trace elements: physiologically regulated essential elements are present in a very similar range in fish from both lakes, while levels of nonessential metals reflect short- or long-term exposure to those elements. The comparison of trace element concentrations in the fish samples from Lake Naivasha showed lower levels of most trace elements after the significant increase of the water level. This study demonstrates that fish are valuable bioindicators for evaluating trace element pollution even in contrasting lakes as long as the way-of-life habits of the species are taken into account.

Distribution of red belly tilapia Coptodon zillii (Gervais, 1848) larvae in Shatt Al-Arab River and East Hammar marsh, Iraq

The larvae of Coptodon zillii were surveyed in Shatt Al-Arab River and East Hammar marsh from January 2015 to December 2015. A total of 127 C. zillii larvae were collected from three stations. The highest number of C. zillii larvae was 78 recorded at station 1 in East Hammar marsh (Mansoury), comprised 61.41% of the total fish larvae collected, and the lowest number (23) was from station 3 in Shatt Al-Arab River near Abu Al-Khaseeb, comprised 18.11% of the total fish larvae collected. C. zillii larvae were found in the study regions from April to October. The peak of abundance was 22.8 larvae/10m² during July at station 1. The lower abundance of larvae was 0.7 larvae/10m² in June at station 2 at the confluence of the Garmat Ali River with Shatt Al-Arab River. Water temperatures in the three sampling stations were similar and ranged from 12°C in December to 32 °C in July. Salinity in station 1 ranged from 1.2‰ in August to 2‰ in June while in station 2 it ranged from 1.03‰ in October to 2.8‰ in July and in the station 3 ranged from 2.7‰ in April to 6.1‰ in December during the study period. Positive correlation was shown between water temperature and salinity in all stations with the number and abundance of C. zillii larvae. The results indicated that the Shatt Al-Arab River and East Hammar marsh are spawning grounds for this species.

Distribution of red belly tilapia Coptodon zillii (Gervais, 1848) larvae in Shatt Al-Arab River and East Hammar marsh, Iraq

The larvae of Coptodon zillii were surveyed in Shatt Al-Arab River and East Hammar marsh from January 2015 to December 2015. A total of 127 C. zillii larvae were collected from three stations. The highest number of C. zillii larvae was 78 recorded at station 1 in East Hammar marsh (Mansoury), comprised 61.41% of the total fish larvae collected, and the lowest number (23) was from station 3 in Shatt Al-Arab River near Abu Al-Khaseeb, comprised 18.11% of the total fish larvae collected. C. zillii larvae were found in the study regions from April to October. The peak of abundance was 22.8 larvae/10m² during July at station 1. The lower abundance of larvae was 0.7 larvae/10m² in June at station 2 at the confluence of the Garmat Ali River with Shatt Al-Arab River. Water temperatures in the three sampling stations were similar and ranged from 12°C in December to 32 °C in July. Salinity in station 1 ranged from 1.2‰ in August to 2‰ in June while in station 2 it ranged from 1.03‰ in October to 2.8‰ in July and in the station 3 ranged from 2.7‰ in April to 6.1‰ in December during the study period. Positive correlation was shown between water temperature and salinity in all stations with the number and abundance of C. zillii larvae. The results indicated that the Shatt Al-Arab River and East Hammar marsh are spawning grounds for this species.

Translocation and new geographical distribution of the invasive Redbelly Tilapia, Coptodon zillii (Gervais, 1848) (Teleostei: Cichlidae) in southern Iran

A new geographical distribution record of the invasive species of Redbelly Tilapia, Coptodon zillii, is reported here from a drainage in southern Iran, based on the discovery of a population at Howba spring. The locality of the new record is now completely dominated by this exotic fish; this location was previously inhabited by native fishes. As tilapia species have a high resilience to harsh environmental conditions, they can easily be translocated to, and establish in, new habitats. Thus, ecological monitoring of this exotic fish species is highly recommended.

Diversity and host distribution of the external gill parasite Lamproglena monodi (Copepoda: Lernaeidae) among Tilapia species in Egypt: Light and scanning electron microscopic studies

Copepods are common component of the ectoparasite assemblages of all kinds of fish, from all environment and ecosystems. Lamproglena monodi is a crustacean copepod known to parasite on several fish species of family Cichlidae in African countries. A few researchers dealt with this parasite in Egypt. A total of 400 cichlids (Redbelly tilapia Tilapia zillii, Nile tilapia Oreochromis niloticus, Mango tilapia Sarotherodon galilaeus and Blue tilapia Oreochromis aureus) were collected during the period of January-December 2015 from River Nile (Golden Island), Giza Governorate, Egypt. The gills and internal organs were examined for the presence of macro-parasites. The taxonomic consistency of the recorded parasite identification was ensured through the entire study. Prevalence, intensity, abundance and seasonal changes for the recovered parasite species were studied. The highest season of infection were noticed in summer and spring all over the experimental study. The recovered parasite species was identified as L. monodi as it exhibited all the characteristic features described previously for the same species. Therefore, the present study demonstrated that tilapia fish in the study area; represented as a new locality records for infection with L. monodi. In addition, O. aureus recorded as a new host record for the present parasite species.