Body Standard Length Research Articles

Morphometric Characterization of Economically Important Populations of Black Tiger Shrimp (<em>Penaeus monodon</em>) Natural Broodstocks in Sri Lanka

Purpose: Presence of morphological heterogeneity and economically superior traits in naturally available brood stock greatly supports yield improvement programs characterizing sub-populations with such traits will provide leverage in doing so. The present study was an attempt to characterise giant tiger shrimp, Penaeus monodon brood stock from Sri Lankan waters to identify whether or not commercially important sub-populations exist based on morphological traits, which can be used for the yield improving P. monodon farming industry in Sri Lanka.Research Method: A total of 495 P. monodon samples were randomly collected from nine areas around the country. Ten selected morphometric traits and the Body Weight (BW) were measured from each. Morphometric measurements were standardized and subjected to multivariate analysis with equation LTs (i)=log10LT(i)[log10 TL(m)/log10 TL(i)]b.Findings: Selected morphological traits were highly correlated with BW showing the highest correlation from hepatic spine width and the lowest correlation by width at the midpoint of the abdominal segment six. In PCA, both PC1 and PC2 accounted for 68.1% of total variation. The scatter plot of PC1 and PC2 indicated that all samples in the nine zones belonged to one population. However, significant variations in BW, standard body length, and abdominal length were observed in different areas and the highest significant BW was recorded in Chilaw, Beruwala, Negombo, and Mullaitivu.Originality/Value: Economically important morphological traits in Penaeus monodon are prominent in a few populations around the country, prompting to selection of individuals from these areas for brood stock improvement programs.

Effects of preserving juvenile rainbow trout (Oncorhynchus mykiss) in formalin and alcohol on body length, mass, and condition factor estimates

Abstract Body length and weight are key parameters measured to provide information about the growth and condition of larval, juvenile, and adult fishes from both the wild and aquaculture. The goal of this study was to evaluate the effects of preservation in formalin and alcohol on juvenile rainbow trout, Oncorhynchus mykiss (Walbaum) standard body length (SL) and weight changes. Standard length (19.43–32.98 mm SL) decreased after 60 days of preservation by an average of 2.98% in 96% alcohol and 2.26% in 10% formalin. In contrast, fish body weight (0.094–0.63 g) decreased in alcohol (31.22%) but increased in formalin (11.65%). These percentage values can be used as correction factors, with the exception of fish body weight in alcohol since the size of individuals affected the magnitude of change. Accordingly, a correction formula accounting for fish weight must be applied (fresh weight (g) = -0.0363 + 1.667 × preserved length). Changes in fish length and body weight in different preservatives resulted in significant differences in the Fulton condition factor, with underestimation in alcohol (fresh F = 1.58; preserved F = 1.20) and overestimation in formalin (fresh F = 1.60; preserved F = 1.92).

Feeding ecology study of Asian redtail catfish, Hemibagrus nemurus (Teleostei: Bagridae), post-sediment flushing in Jenderal Soedirman Reservoir Central Java, Indonesia

Abstract. Wibowo DN, Sukmaninggrum S, Widyastuti A, Soedibya PHT, Rahayu NL. 2024. Feeding ecology study of Asian redtail catfish, Hemibagrus nemurus (Teleostei: Bagridae), post-sediment flushing in Jenderal Soedirman Reservoir Central Java, Indonesia. Biodiversitas 25: 2315-2322. Hemibagrus nemurus Vallenciennes 1840 is among the valuable fisheries commodities in Banyumas District and led to high exploitation. Research on H. nemurus is essential for its conservation, including its feeding ecology. Feeding ecology studies of H. nemurus have been conducted previously, but the relative examination of this Asian redtail catfish is lacking in Jenderal Soedirman Reservoir, Central Java, Indonesia. Therefore, this study aimed to investigate the feeding ecology of H. nemurus, focusing on post-sediment flushing in the Jenderal Soedirman Reservoir in 2022. Specimens were collected at nine sampling sites in the reservoir during morning and evening sessions, with observed parameters including mouth position, intestine length ratio, intestine content, and the index of preponderance (IP). The results showed that H. nemurus had a subterminal mouth position as well as shorter to slightly longer intestines than the standard body length (SL). Based on the IP value, diets inside the intestine were dominated by animal materials, namely fish compounds. Hence H. nemurus seemed to be predatory considering its detected piscivorous habits. The identified mouth position, intestine length, and dominant diets were similar to the reports on the same species from other regions. These feeding ecology data would provide essential information for the fisheries and conservation of H. nemurus in Jenderal Soedirman Reservoir.

Biological indicators and commercial exploitation of main fish and river crayfish species of the Zaporizhzhia (Dnipro) reservoir

Aim: To analyze and summarize the biological indicators of the main industrial fish and river crayfish species in the Zaporizhzhia (Dnipro) reservoir under conditions of fishery exploitation. Methods: Biological analysis of fish was conducted according to classical methods in ichthyology, using the following parameters: standard and absolute body length, individual mass, gender, feeding coefficient. Crayfish, caught in fishing gear, underwent morphometric measurements to determine individual mass and gender. Biological sampling was carried out during the vegetation period of 2023 during both control and commercial fishing in the Zaporizhzhia (Dnipro) reservoir at three sites differing in hydrology and degree of anthropogenic impact. Research results: According to the data from the Department of the State Agency of Reclamation and Fisheries Management in Dnipropetrovsk Oblast, during 2023, 140,504 tons of fish were caught in the Zaporizhzhia (Dnipro) reservoir, nearly 8 times less than in 2021. In 2021, 1078.25 tons of aquatic resources were caught, which is 8 % less than in 2020. Silver carp was the dominant fish species in 2022, accounting for 80.5 % of the total catch in the reservoir. Herbivorous fish species accounted for 5.4 % of the catch, roach - 3.3 %, bream - 2.3 %, perch - 2.0 %. Based on the conducted research, recommendations have been provided regarding the establishment of forecasts and limits for the extraction of aquatic resources from the Zaporizhzhia (Dnipro) reservoir for the year 2024. Conclusions: The Zaporizhzhia (Dnipro) reservoir has potential for the development of fishing, fish farming, and aquaculture in the Prydniprovsky region. The research results suggest that limits can be set on the catch of certain fish species: bream- up to 210 tons, pike-perch - up to 42 tons, roach - up to 350 tons, and perch - up to 138 tons. However, the catch of silver carp, bleak, sprat, herbivorous fish, and sun-perch is recommended to be unrestricted. The forecasted catch of crayfish is within 1 ton. The catch of other aquatic resources should also be conducted within forecasted levels

РАЗМЕРНО-ВЕСОВОЙ СОСТАВ И МОРФОЛОГИЧЕСКАЯ ХАРАКТЕРИСТИКА ДЕВЯТИИГЛОЙ КОЛЮШКИ PUNGITIUS PUNGITIUS (GASTEROSTEIDAE) ИЗ ОЗЕРА ПРИЛИВНОГО (ЮГО-ВОСТОЧНАЯ КАМЧАТКА) ЗИМОЙ 2022-2023 ГГ

Size-weight composition and morphology of the nine-spined stickleback Pungitius pungitius from Lake Prilivnoe (southeast of Kamchatka) from December 2022 to March 2023 were studied. The average length of fish in 4 months increased from 30.5 to 55.3 mm, and the average individual weight of fish increased from 0.5 to 2.1 g, respectively. The largest scatter of data was observed for the anteanal, antepectoral, antedorsal and anteventral distances, the length of the caudal peduncle and the length of the head. As body length increases relative to body length, head length, anteanal distance, and antepectoral distance increase. The antedorsal distance, anteventral distance and the length of the caudal peduncle decrease with growth relative to the standard body length. As a result of the research, the variability of the morphological characteristics of the nine-spined stickleback that lives in this reservoir and is caught in one place.

Weight prediction of intensively reared gilthead seabream Sparus aurata from morphometric traits measured in images

The objective of this study was to establish an accurate body weight (BW) prediction model for gilthead seabream Sparus aurata of 50–1000 g. Three thousand three hundred twelve (3312) fish were individually weighed and photographed. Traits measured from the images were total body length (TBL), fork body length (FBL), standard body length (SBL), body height (BH), head length (HL), eye diameter (ED), body area (BA, without fins), head area (HA), and eye area (EA). SBL, BH, BA, BA/SBL, and BA/BH showed a strong association with BW (correlation coefficients, r: 0.96–0.99). These traits were selected to proceed with the regression analysis. Simple, multiple linear, and 2nd-order polynomial regressions were applied to the whole data set and three BW subgroups of interest during gilthead seabream rearing (i.e., 50–100 g, 100–500 g, 500–1000 g). The prediction of BW from the whole data set was more accurate than from each BW subgroup. The models with the highest coefficient of determination (R2) and the lowest errors (mean absolute percentage error, MAPE) were either the power regression of BW with BA (R2: 99.0%, MAPE: 5.8%) or the multiple linear regression of BW with SBL, BA, BA/SBL, and BA/BH (R2: 98.6%, MAPE: 5.1%) as predictors. The accuracy of the two models is considered quite similar, and for reasons of simplicity, the power regression is advantageous, requiring only one trait to be measured (BA). The models identified in the present study can help to further develop the accuracy of machine vision-based systems for gilthead seabream BW measurement.

Biological particulars of the sun perch – Lepomis gibbosus (linnaeus, 1758) from the Cuciurgan reservoir-cooler

The sun perch was recorded for the first time at the mouth of the Dniester in 1952. In the ichthyofauna of the Cuciurgan harbor in 1965. Starting with the second half of the 1960s, it was not recorded in the Cuciurgan refrigeration lake until the 2000s. From 2004, unique specimens were recorded, which probably hit, together with the water pumped from the Turunchuk arm. The share of sun perch in the control catches of Cuciurgan Refrigerating Lake increased from 0.5% in 2008 to a record 15.7% in 2017. The high abundance of sun perch in a short period is explained by the type of portioned reproduction, high prolificacy, early age of sexual maturity and also care for offspring. In the Cuciurgan reservoir, mature sun perch females weighing 7.2 g were captured, and with a weight of 13.4 g they were identified in stage IV of gonad maturation. The sun perch of the Cuciurgan Refrigerating Lake is characterized by a high growth rate, thus the maximum standard body length is greater than 17 cm with a mass of 220 g. A polynomial model was used to approximate the sun perch abundance monitoring data of degree IV (reliability coefficient R2 = 0.8211), which determines the characteristic of rapid growth of invasive fish species, then followed for 4 years a stage of stabilization of the population, after which it is characterized by a decrease in abundance, due to the appearance of a foreign species in the tank – the mud crab.

The impact of various carbon nanomaterials on the morphological, behavioural, and biochemical parameters of rainbow trout in the early life stages

With the increasing production and the number of potential applications of carbon nanomaterials, mainly from the graphene family, their release into the natural environment, especially to aquatic ecosystems, is inevitable. The aim of the study was to determine the effects of various carbon nanomaterials (graphene nanoflakes (GNF), graphene oxide (GO), reduced graphene oxide (RGO) and silicon carbide nanofibers (NFSiC) in the concentration of 4 mg L−1 on the early life stages of the rainbow trout Oncorhynchus mykiss. The survival rates of O. mykiss were not affected after 36 days of exposure to studied materials, except for RGO, which caused significant mortality of both embryos and larvae compared to the control conditions. Larvae exposed to GO and NFSiC were characterized by a smaller standard body length at hatch, whereas at the end of the experiment, the growth of fish exposed to all materials was accelerated, especially in GO and RGO treatment, in which higher body weight and length were accompanied by lower volume of the yolk sac. Neither the markers of the oxidative damage nor the antioxidant enzymes activities were significantly affected in embryos, newly hatched larvae and larvae after 26-day exposure to studied carbon nanomaterials. Also, no neurotoxic effect expressed by the activity of the whole-body acetylcholinesterase was observed. Nevertheless, the significant increase in the velocity and the overall activity of larvae exposed to GNF (not investigated after exposure to other materials) must be highlighted. The most pronounced effect of RGO might be connected with its large particle size, sharp edges, and the presence of TiO2 nanoparticles. The results indicate for the first time that various carbon nanomaterials potentially released into aquatic ecosystems may have serious developmental implications for the early life stages of salmonid fish.

Morphological characteristics of carp (Carassius Gibelio) in the conditions of pond fish farming in Uzbekistan

Silver carp has a huge range that distributed in Eurasia and America. Interest was aroused by the use in fish farming, high taste qualities in particular. In this research, the material was collected in October - December 2021 in the ponds of the fish hatchery of the Research Institute of Fisheries of Uzbekistan. During the experiments, the measured traits were calculated in the form of indices, showing them as a percentage of the standard body length for each individual. The results showed that the minimum and maximum body weight was 13 and 88, respectively. However, the average was 32.8 mm. It was observed that average hard rays in the dorsal fin was 2, but this was 4.5 in the case branched rays in the anal fin. Noteworthy, a comparison of the data shows that the index variability with the “truss-protocol” is significantly lower.

Comparative brain analysis of wild and hatchery reared Mahseer (Tor putitora) relative to their body weight and length.

The present study was aimed at comparing the brain size of mahseer (Tor putitora) in relation to their body weight and standard length, to investigate the potential impact of rearing environment on brain development in fish. The weight of the brain and three of its subdivisions cerebellum (CB), optic tectum (OT), and telencephalon (TC) were measured for both wild and hatchery-reared fish. The data was analysed using multiple analysis of covariance (MANCOVA), analysis of covariance (ANCOVA), and discriminate function analysis (DFA). We found the fish reared under hatchery conditions exhibit smaller brain size related to body weight, when compared to the wild ones. A significant (p<0.5) difference was observed in the length of CB and OT concerning the standard body length while no significant difference was found in TC of the fish from both the origins. The results of the current study highlight a logical assumption that neural deficiency affects the behaviour of fish, that's why the captive-reared fish show maladaptive response and face fitness decline when released to the natural environment for wild stock enhancement. The current study concluded that hatchery-reared fish exhibit variations in gross brain morphology as compared to their wild counterpart.

High growth performance in the early ontogeny of an amphidromous fish, Ayu Plecoglossus altivelis altivelis, promoted survival during a disastrous river spate

AbstractAlthough river floods and spates have a major influence on fish populations, few studies have examined the selective pressure on individuals and traits that favour their survival. In this study, the factors that potentially affect the survival of an amphidromous fish species, ayu Plecoglossus altivelis altivelis (Temminck &amp; Schlegel), during a major spate were examined. Using otolith analyses, ayu in the Takahashi River, Okayama, Japan, were compared before (April; n = 50) and after (September; n = 32) a spate with regard to their respective hatch‐date distributions, standard body length and age at upstream migration, age at metamorphosis, and larval and juvenile growth rates. When comparing juvenile traits, surviving adult ayu grew faster than individuals collected before the spate. These findings suggest that juvenile growth rate is a key factor for enhancing subsequent survival and highlight the importance of conserving suitable nursery habitats to enhance fish survival during future floods.

Zooplankton body size is filtered by a thermo‐oxygenic niche at the regional scale

AbstractAimThere is ongoing debate regarding the extent to which body size is selected by the environment. To address this issue, we assessed how thermo‐oxygenic conditions select body size of rotifer species composing a regional species pool.LocationApproximately 600 different water bodies in Sweden.TaxonRotifers (188 species).MethodsData were acquired from previously published studies. For the environmental parameters, we conducted principal component analysis (PCA) to recognize the pattern among the species‐specific thermal and oxygenic preferences of rotifers of different ecology. We assigned a standard body length to each species. We performed phylogenetically correlated analyses to evaluate the relationships between body length and the parameters that were selected as PCA drivers.ResultsThermal and oxygenic tolerance ranges, designated by the differences between the minimum and maximum of species occurrence, were grouped separately from the optima designated by the conditions referring to the highest species abundance, according to PC1 versus PC2. The parameters representing temperature and oxygen occupied opposite positions on the PC2 axis. Body size selection was driven by both temperature and oxygen, but the cues for this selection differed; species with higher thermal optima were smaller, while species with wider oxygen tolerance ranges were larger.Main conclusionThe body sizes of rotifer species are filtered by both thermal and oxygenic conditions. Selection is driven by tolerance ranges and optima. Oxygenic conditions are as important as thermal conditions in body size selection within a species assemblage.

Anatomy of the digestive system of lumpfish (Cyclopterus lumpus) as an adaptation to puffing behavior.

The first description of the histology of the digestive tract of the lumpfish Cyclopterus lumpus showed an adaptation for collecting and storing water. The morphology of this species' tract is mostly typical of carnivorous fishes, having a sac-like stomach for storage and a relatively short intestine of approximately 1.2× the standard body length. The esophagus is relatively short (0.13× standard body length) and thick-walled; it has a thick muscular coat, and its thickness changes from 0.4 to 1 mm during contraction. The stomach has well-developed gastric glands and is divided into the histologically distinguishable cardiac, fundus, and pyloric parts. The intestine has the same structure throughout its entire length. The water-holding ability of lumpfish is provided by well-developed muscles in the esophagus and stomach distensibility, which differs morphologically from the method used by Tetradontidae and Diodontidae species, who store water in the caudal part of the esophagus. The morphology of the digestive tract proved that this species is an intermediate between Tetradontidae and Diodontidae, which could inflate their bodies by swallowing certain amounts of water, and other fishes which are not able to do so. Results of the work extend current knowledge on the morphological capability of the digestive system of teleost fish, providing water-blowing behavior.

Comparative Anatomy of Wild Adult African Catfish (Clarias garIepinus) Ovary During Rainy and Dry Periods in Zaria, Nigeria

The study investigated effects of rainy and dry periods on the ovaries of wild adult Clarias gariepinus in Zaria, kaduna State Nigeria. Twenty-four wild adult catfish with average weight of 1000.00 ± 0.00 gm was used during both periods. They measured a standard body length of 50.17±1.01 cm (rainy) and 44.83 ± 2.09 cm (dry). The fish were sourced from Zaria dam and transported live to Gross Anatomy Laboratory in Ahmadu Bello University Zaria. Each fish was euthanized using tricaine anaesthetic at 8 drops/litre of water. The ovaries were extracted, weighed and fixed in Bouin’s fluid for 24 hours, and processed histologically. Grossly, the ovaries were observed to be well-developed and highly vascularized during rainy period while, regressed and poorly vascular- ized ovaries were seen during dry pe- riod. The mean weight of the ovaries (0.025) and Gonado-somatic index (GSI) value (0.034) were significantly higher during rainy period. Histologically, the ovaries were predominated by vitellogenic and post-vitellogenic follicles during rainy period while, pre-vitellgenic follicles predominates dry periods. The tunica albuginea and interstitial connective tissues were thin during rainy period but thick during dry period. Hence, the result of this study revealed that wild adult catfish spawns during rainy period while, dry period is characterized by low gonadal activities in Zaria, Nigeria.

Effect of rearing systems and dietary probiotic supplementation on the growth and gut microbiota of Nile tilapia (Oreochromis niloticus) larvae

The establishment of the early-life gut microbiota plays an important role in fish development and influences the host's health status and growth performance. Different rearing conditions can impact the initial colonization of the gut microbiota, while the addition of probiotics may also affect such colonization. However, how this may affect fish larvae survival and growth remains largely unexplored. In this study, 3-day old Nile tilapia embryos were hatched until 9 days post fertilization (dpf) in three systems, including one flow-through system (FTS) and two identical recirculating aquaculture systems (RAS). When feeding started at 10 dpf, tilapia larvae in the FTS and one of the RAS were fed with a control diet, while larvae in the second RAS were fed with the control diet coated with B. subtilis spores (RASB). The feeding trial lasted 26 days, from larvae to fry stage, during which the survival, growth performance and gut microbiota were analyzed. The larvae reared in FTS showed significantly lower survival than those in RAS and RASB, while no differences were observed in fish growth and apparent feed conversion ratio between treatments. Different rearing systems resulted in different gut microbiota compositions, which strongly correlated with the survival rate and standard body length at harvest. Cetobacterium was enriched in RAS and RASB, while was barely detected in the gut of FTS-reared tilapia fry. Probiotic supplementation increased the relative abundance of beneficial Bacillus in fish gut. Our findings indicate that rearing fish larvae in RAS supports better survival compared to FTS, while dietary probiotic supplementation further modulates the gut bacterial composition and stimulates presence of beneficial bacteria during early life.

Ichthyofauna of Gibe Sheleko National Park and some morphometric relationships of fish of the tributary rivers, Southern Ethiopia

Understanding of Ichthyofaunal diversity is a major gateway for the conservation of waterbodies in the world. Ethiopia has a rich Ichthyofaunal diversity, although they are poorly known. This study was carried out in two tributary rivers (Gibe and Wabe) of Gibe Sheleko National Park to investigate Ichthyofaunal diversity and morphometric characteristics of fish. By using monofilament gill-nets, fish were collected, identified and measured their morphometric. A total of 10 species were identified, dominated by Synodontis schall, followed by Labeobarbus nedgia and Labeobarbus intermedius. According to the Index of Relative Importance, S. schall was also first (49.13%), followed by L. intermedius (15.49%). Gibe River had a higher number of species than Wabe River. The Shannon Diversity Index in Gibe River was also higher (2.09) than Wabe (1.84) during the dry season, but lowest in the wet season (1.52 and 1.57 respectively). Synodontis schall had the largest girth, but Clarias gariepinus had the largest eye diameter and body weight. Heterobranchus longifilis was first in total, fork and standard body length. Generally, differences in sampling habitats and fishing effort might have contributed to discovered variants findings. Fishery development should be implemented in the Park to use the fish resource sustainably.

Sex dimorphism of Yunnanilus analis and its habitat adaptation in Xingyun Lake, Yunnan, China.

Yunnanilus is a group of endemic fish inhabit in Yun-Gui Plateau and its adjacent areas. They show the characteristic of sex dimorphism, which could be an important reason for their adaptation to karst habitats. Here, we used Yunnanilus analis as the model to understand the sex dimorphism characteristics and its adaptation to the karst habitats. The sex dimorphism, female fecundity, and food specialization of Y. analis were investigated in Xingyun Lake, Jiangchuan, Yunnan. Our results showed that Y. analis exhibit sex size dimorphism (sex dimorphism index=0.23; female with larger body size). There were stains on the transverse sections at females body, but not in males. Males had dark longitudinal lines at their body sides. Morphological differences between males and females were confirmed by the results of one-way analyses of variance (ANOVA), multivariate statistical analyses, principal component analyses, discriminant analyses, and one-way analyses of similarity (ANOSIM) on total length, standard body length, fork length, head width vs. heal length, and the distance between the starting point of ventral fin to the starting point of pectoral fin vs. standard body length. Fecundity of female fish was 1364.5±489.3 (470-2430) eggs, which were positively correlated with their body size. Both female and male Y. analis mainly feed on Chironomid larvae and mayfly naiads. Their food composition was somehow similar, with significantly statistical difference. In conclusion, fecundity selection pressure and food specialization should be the main factors contributing to the evolution of Y. analis' sex dimorphism. More importantly, sex dimorphism of Y. analis is a significant adaptation to the karstic habitats.

Comparative anatomy of wild adult tilapia (&lt;i&gt;Oreochromis niloticus&lt;/i&gt;) testes during rainy and dry periods in Zaria, Nigeria

The study was undertaken to investigate the effects of rainy and dry periods on the gross and histology of the testes of Oreochromis niloticus in Zaria, Kaduna State, Nigeria. Twenty-four adult wild tilapia fish with average weight of 234.74±5.20 gm and 177.84±31.07 gm was used during rainy and dry periods, respectively. They measured a standard body length of 23.50±0.29 cm and 22.17±0.73 cm during rainy and dry periods, respectively. The fishes were sourced from Zaria dam and transported live in open plastic troughs containing clean water to the Gross Anatomy Laboratory in the Department of Veterinary Anatomy, Ahmadu Bello University Zaria. Each fish was euthanized using tricaine anaesthetic at 8 drops/litre of water. The testes were extracted, weighed and fixed in bouin’s fluid for 24hours. Each testis was then dehydrated through series of ascending concentrations of ethanol, cleared in xylene, embedded in paraffin wax and sectioned at 5µm. Hematoxylin (H) &amp; Eosin (E) were used for histological evaluation. Grossly, the testes of O. niloticus were whitish, non-lobulated and well developed during both rainy and dry periods. Each testis had a smooth lateral and medial edge. Seminal vesicles and Bulbourethral glands were absent. The average weight of both testes shows insignificant variation across both periods (0.458). The Gonado-somatic index value was insignificantly higher during rainy period (0.159) compare to dry period. Histologically, the lumen of seminiferous lobules was filled with spermatozoa during both rainy and dry periods. The tunica albuginea and interstitial connective tissues were thin across both periods. In conclusion, Gross and histological results which coincide with the values of Gonado-somatic index revealed that wild adult tilapia fish spawns during both rainy and dry periods in Zaria, Nigeria.&#x0D; Keywords: Gonado-somatic index, Testes, Seminiferous lobules, Spermatozoa, Wild Tilapia, Zaria dam

Assessment of cytotoxicity in gills of fish Labeo rohita reared in untreated and treated sewage water.

The unregulated discharge of untreated municipal sewage water to the natural water bodies is a major threat to the aquatic ecosystems. In the present study, the fingerlings of Labeo rohita were exposed to treated sewage water and 1/10th of LC50 and 1/20th of LC50 of untreated sewage water (UT) obtained from sewage water treatment plant, Ludhiana, India. After determining 96-h LC50 value of UT, fingerlings were divided into four groups: control, treated, 1/10th of LC50 UT and 1/20th of LC50 UT and exposed for a period of 2months. Our study revealed that 1/10th LC50 UT and 1/20th LC50 UT groups had significant reduction in body weight, total body length, standard body length and gills somatic index in comparison with the control and treated groups. Histopathological alterations in cellular structure of gills such as ruptured primary lamellae, broken secondary lamellae, distorted chloride cells and goblet cells, missing lamellae and disintegrated lamellar epithelium were also observed in 1/10th LC50 UT and 1/20th LC50 UT groups. A significantly high frequency of micronucleated (MN) cells was observed in 1/10th LC50 UT and 1/20th LC50 UT groups along with the presence of binucleated cells (BN), elongated nuclei (EN) and nuclear buds in gill cells. Genotoxic nature of UT was further confirmed from significantly high values of genetic damage index (GDI) and percentage (%) DNA damage in gill cells of fingerlings exposed to sub-lethal concentrations of UT. The study concluded that untreated sewage water has potential to induce anatomical and physiological defects in gills cells and the severity of toxicity increases with the increase in duration of exposure.

Comparative anatomy of wild adult tilapia (&lt;I&gt;Oreochromis niloticus&lt;/I&gt;) ovary during rainy and dry periods in Zaria, Nigeria

The study was undertaken to investigate the effects of rainy and dry periods on the gross and histological features of ovaries of Oreochromis niloticus in Zaria, Kaduna State, Nigeria. Twenty-four (24) adult wild tilapia fish with average weight of 300.17 ± 25.71 gm and 229.94 ± 23.68 gm was used during rainy and dry periods, respectively. They measured a standard body length of 24.00 ± 0.76 cm and 23.83±0.60 cm during rainy and dry periods, respectively. The fish were sourced from Zaria dam and transported live in open plastic troughs containing clean water to the Gross Anatomy Laboratory, Department of Veterinary Anatomy, Ahmadu Bello University Zaria. Each fish was euthanized using tricaine anaesthetic at 8 drops/litre of water. The ovaries were extracted, weighed and fixed in Bouin’s fluid for 24 hours and processed histologically. Grossly, the ovaries of O. niloticus were highly vascularized and well developed during both rainy and dry periods. The average weight of both ovaries showed insignificant variation across the periods (0.125). The Gonado-somatic index value was insignificantly higher during rainy period (0.115) compared to dry period. Histologically, the ovaries were predominated by vitellogenic and post-vitellogenic follicles across both periods of the year. The tunica albuginea and interstitial connective tissues were thin during both periods. In conclusion, the results in this study revealed that adult wild tilapia fish had developed ovaries with predominant mature follicles during both rainy and dry periods suggesting that adult wild tilapia fish spawns during both rainy and dry periods in Zaria, Nigeria.&#x0D; Keywords: Follicles, Gonado-Somatic Index (GSI), Ovaries, Wild tilapia, Zaria dam