Gonadal Maturation Stages Research Articles

Gametogenic cycle of the marine gastropod Trophon geversianus in a harsh Patagonian intertidal environment

ABSTRACT The edible marine gastropod Trophon geversianus shows a large geographic distribution along the southern tip of South America, inhabiting both rocky intertidal and shallow subtidal zones, with distinct behavioural responses to environmental stressful conditions (desiccation, temperature amplitude and high irradiation). Nevertheless, its reproductive biology has been poorly reported to date. We studied the gametogenic cycle of an intertidal rocky shore population from northern Patagonia (Argentina), in order to investigate the relation between gonadal changes and seasonal environmental variables. Mature individuals were taken monthly during an annual reproductive season and processed by standard histology procedures (haematoxylin and eosin). Adults of T. geversianus registered different gonadal maturation stages along the year, showing a marked seasonal variation without a resting period. The highest gamete evacuation season in both sexes was registered when the environmental stress was minimum (winter), while a greater number of individuals with gonads in proliferation and growth were predominant during maximum environmental stress (summer). The reproduction pattern presented an extended period of evacuation and a short phase of non-evacuation, associated to drastic seasonal environmental changes in the intertidal zone of Atlantic Patagonia. This information is useful to protect the resource and assure the sustainability of intertidal populations.

Determination of gonosomatic index, hepatosomatic index and condition factor in Liza carinata (Valenciennes, 1836)

Morphometric of examination of gonads of Liza carinata were performed for one year (October 1995 – September 1996) to study the maturation development. Monthly variation in gonado – somatic index (GSI) were noticed, that started with low values during October and November. Significant increase in (GSI) was recorded during the period December - April with the peak in February (3.59 in males & 9.33 in females) followed by a significant decline during May – September. Variations in hepato – somatic index (HSI) were related to feeding activity rather than gonadal maturation. Peaks of HIS & GSI were recorded at similar time period. On the contrary, the somatic condition factor (SCF) was closely related to gonadal maturation stages. Lower values (SCF) were recorded during winter months which showed higher values in GSI.

Biology of rotan firebrand Perccottus glehni Dybowski, 1877 in floodplain lakes of the Oka River

According to the results of accounting surveys with ring nets in highly overgrown floodplain lakes of the upper reaches of the river Oka found that the core of ichthyocenosis includes an invasive species — rotan-firebrand. The rattan sample from the ring net catches was represented by seven age groups, with a predominance of fish aged 3–4+. Indicators of the length and mass of the rattan vary significantly within the age groups due to the portionality of its spawning in lakes. Rotan growth in floodplain lakes of the Oka basin is on average higher than in riverbed ponds. The sex ratio in the younger age groups is characterized by a predominance of males over females, and vice versa in the older ones. The rotan in Tulchinsky Lake reaches sexual maturity at the age of 2–3+ with a body length of 4–7.7 cm and a weight of 1.8–11.3 g. The largest amount of rotan in the IV stage of gonad maturity is observed in July and is associated with the portionality of spawning. The main food of rotan in the lake are gastropods; substitutive — dragonfly larvae, chironomids, fish; forced — water bugs and macrophytes (duckweed). Rotan cannibalism is observed in fish with a length of more than 15 cm in the autumn period. The concentration and biomass of rotan in the areas of the lake covered with floating vegetation is on average eight times higher than in the open areas of the water area.

Biological aspects of brown-marbled grouper (Epinephelus fuscoguttatus) from Taka Bonerate National Park, District of Selayar Islands, South Sulawesi, Indonesia

Abstract. Fatma, Mallawa A, Najamuddin, Zainuddin M, Ayyub FR. 2022. Biological aspects of brown-marbled grouper (Epinephelus fuscoguttatus) from Taka Bonerate National Park, District of Selayar Islands, South Sulawesi, Indonesia. Biodiversitas 23: 1140-1153. Knowledge regarding biological aspects of fishes such as the brown-marbled grouper can provide important information for fisheries management. This research was conducted from February 2020 to February 2021 to determine the length-weight relationship, condition factor, gonad maturity stage and spawning pattern, size at first maturity and feeding habits of brown-marbled groupers in Taka Bonerate National Park. The sample caught comprised 1042 brown-marbled groupers with a total length (TL) range of 23-97 cm and a weight range of 0.5-17.6 kg. The length-weight equation was W: 0.0001?L2.5955 (R²: 0.8935). For male brown-marbled grouper (n: 569), TL range was 47-97 cm, weight range 1.65-17.60 kg, regression equation W: 0.0002?L2.4731 (R²: 0.7716), condition factor range 0.56-2.36 (mean 1.236±1.019), and length at first maturity 66.34 cm. For female brown-marbled grouper (n: 473) TL range was 23-73 cm (mean 46.84 cm), weight range 0.50-6.6 kg (mean 2.23 kg), regression equation W: 0.0007?L2.1057 (R²: 0.7416), condition factor range 0.55-2.17 (mean 1.225±1.018), and length at first maturity 45.43 cm. The growth pattern was negative allometric with regression coefficient b < 3 for both sexes separately and combined. The majority of both male and female fish caught had mature gonads with indications of a partial spawning pattern. The fish diet was carnivorous, predominantly piscivorous (74%), with gut contents comprising 64% unidentified fish and 26% unidentified decapod crustaceans. Over-exploitation of fish can cause negative impacts on populations, so the relationship between length and weight, condition factors and maturity level gonad of fish can be used in fisheries management.

Sensory profiling, liking and gonad composition of sea urchin gonads fed synthetic or natural sources of β-carotene enriched diets

Sea urchin gonads are considered a prized seafood product. Their market price depends on quality and appearance, mainly evaluated through colour. The desirable yellow-orange colour is determined by carotenoids deposition in the gonads, mainly the accumulation of echinenone, which depends on availability, uptake and bioconversion of β-carotene from dietary sources. Two β-carotene sources, a synthetic (SYN) and a natural (paprika, PAP) source, were tested at low (L) and high (H) incorporation target levels (100 and 250 mg β-carotene kg−1 feed) in diets for Paracentrotus lividus. A non-supplemented diet was used as a control (CTRL) diet. After eight weeks of feeding, all diets effectively increased gonad weight and somatic index in both sexes, without significant differences between treatments. Total carotenoid content and profile, lightness (L*) and texture of gonads did not vary significantly among dietary treatments. However, gonad redness (a*) and yellowness (b*) values were significantly higher in urchins fed the L_SYN diet than in those fed either with the CTRL or L_PAP diets; female displayed higher values than male. L_SYN also showed higher consumers´ acceptance when compared to the other diets and female displayed higher acceptance rates than male, probably due to the fact that females were more orange, appealing and pleasant compared with the yellow, grainy and not appealing males. Male fed L_SYN diet exhibited similar colour and carotenoid content compared to wild animals in the same stage of gonad maturation (stage III), but female differed significantly; however, neither of the sex demonstrated acceptance differences in relation to their wild counterparts. Diets with the lower β-carotene inclusion induced changes in gonad colour but not in carotenoid pigments. This suggests that gonad colour is not exclusively modulated by dietary carotenoid supplementation and that it may be affected by other sex-dependent nutritional or metabolic factors.

ELUCIDATING THE GONADAL DEVELOPMENT AND SEX DIFFERENTIATION OF THE RICE PADDY EEL, Monopterus albus (Zuiew, 1993), BASED ON GONADAL HISTOMORPHOLOGY AND STEROID HORMONE LEVELS

The establishment and survival of the population of species in their breeding ground can be attributed to the species’ reproductive characteristic and capacity. The Monopterus albus species is an introduced fish in the Philippines. It is a protogynous hermaphrodite which has a natural ability for sex reversal. This study describes the histomorphology of the different stages of gonadal maturation and determines the concentration levels of the steroid hormones 17ß-estradiol (E2) and testosterone (T) in the blood plasma. These aim to a further understanding on the gonadal development and sex differentiation of the rice paddy eel as a hermaphroditic fish. Fish samples were collected randomly from farm ponds located in three provinces within the island of Luzon, Philippines. The sexual identity of the fish was categorized based on the presence or absence of ovarian and testicular tissues. Histological analysis of the gonad showed that immature, maturing-matured female gonad exhibited ovarian tissues of varying stages. The intersex gonad showed the existence of both ovarian and testicular tissues. Enzyme-linked immunosorbent assay (ELISA) was used to determine the concentration levels of gonadal steroid hormones. Differences in the concentration levels of the two hormones were evident across all the stages of gonad maturation. The functional role of these hormones in vitellogenesis and spermatogenesis leads to the development of this sex-changing gonads. This reproductive characteristic contributes to our understanding of the reproductive success of hermaphroditic fish.

Reproductive biology of male Euthynnus affinis (Cantor, 1849) in Kedonganan Bali

E. Affinis is one of the important economic fishery commodities. E. Affinis fishing has exceeded the optimum limit. Utilization of E. Affinis has exceeded the optimal limit with high fishing pressure. The reproductive biology of E. Affinis needs to be known to ensure its presence in the wilderness. The purpose of this study was to determine the growth pattern, Gonad Maturity Stage (GMS). The study was carried out in February, April, June to December 2020. The data were collected through direct observation at the Fish Landing Base (PPI) Kedonganan. The sampling technique used in this study was purposive stratified sampling. The results obtained that the growth pattern of male E. affinis is W=0,021L2,9542, and the growth of male E. affinis is isomeric with a length distribution of 25-65cmFL. The size of the first gonad maturity (Lm) is 45.53 cm FL. Gonad Maturity Level (TKG) in macroscopic’s dominated by immature gonad fish.

The dynamics of the liver weight and liver indices in the course of gonad maturation of gadid species on Eastern Kamchatka

Longterm data on the liver weight, hepatosomatic (HSI) and gonadosomatic (GSI) indices of walleye pollock, Pacific cod and saffron cod are analyzed on Eastern Kamchatka in seasonal aspect and in the course of gonad maturation. Individual values of the indices extensively vary and depend on the fish body length, season and stage of gonad maturity. The dynamics of the HSI is agree to the dynamics of the GSI during the year and depending on gonad maturity. The maximum values of the HSI are typical for walleye pollock and Pacific cod individuals with the gonads of the III stage of maturity. The maximum values of the index in saffron cod are found in mature individuals with immature gonads. The minimum values are demonstrated by the fish with the gonads at the stage of final spawning or of post-spawning recovery. During the annual reproduction cycle males and females of walleye pollock and cod realize different scenarios of spending and accumulating liver fat. Whereas the maximum HSI is observed in the fish with the gonads at the III maturity stage, the minimum values in males are typical for individuals with smelting gonads, and in females – on finishing the spawn. That can be connected to possible feeding for the individual. Liver weight and liver index can increase in males just shortly after finishing spawning, in females that is found only at the stage of post-spawning recovery.

Otolith "spawning zones" across multiple Atlantic cod populations: Do they accurately record maturity and spawning?

Specific changes identified in the otolith macrostructure of Northeast Arctic cod as "spawning zones" are presumed to represent spawning events, but recent experimental studies have challenged this relationship. Because these zones are not routinely recorded outside of Norway, otoliths from multiple Atlantic cod populations with different life history and environmental traits were first examined to see if spawning zones could be identified as a general characteristic of cod. Then, a large archival collection of cod otoliths was used to investigate temporal changes in the occurrence of spawning zones and test for correlations between maturity at age derived from otolith spawning zones and gonad maturity stages. This study shows that spawning zones likely are a universal trait of Atlantic cod and not limited to certain environments or migratory behaviors as previously proposed. Maturity at age derived from spawning zone data showed trends consistent with those from gonad examinations. However, spawning zones appear to form with a one- or two-year lag with sexual maturity, which is suspected to reflect a stabilizing of energy partitioning after the first spawning events. Our results illustrate the potential for use of spawning zones, for example in species or populations with limited available maturity data, and highlights the need for addressing the physiological processes behind their formation.

Influence of 17β-oestradiol (E2) and 17α-hydroxyprogesterone (OHP) on ovarian maturation in Penaeus semisulcatus De Haan, 1844 (Decapoda, Dendrobranchiata, Penaeidae) from the Mediterranean Sea off Alexandria, Egypt

Abstract This study searches to provide appropriate conditions to trigger spawning in Penaeus semisulcatus in aquaculture. The aim was to test the effect of 17β-oestradiol and 17α-hydroxyprogesterone on ovarian maturation and to study the correlation between the different stages of ovarian maturation and hormonal levels in the ovaries, hepatopancreas, and haemolymph. Female shrimps were collected from Ras El-Tin beach and the fishing port to Abu Qir Bay of the Mediterranean Sea off Alexandria, Egypt from June 2018-August 2019. Shrimps were individually weighed and subsequently killed by thermal shock at a maximum temperature of 45°C. Gonadosomatic and hepatosomatic indices were calculated. The correlation between the gonadosomatic and hepatosomatic indices indicates the presence of endogenous and exogenous vitellogenesis. The haemolymph, hepatopancreas, and ovaries were studied by stereo- and electron microscopy. From 15 females in each season the mentioned tissues were isolated for the extraction and quantification of steroid hormones during the different stages of gonadal maturation using radioimmunoassay. An ecdysteroid- and steroid-extraction protocol was applied. Aliquots were collected from the haemolymph to identify 17β-oestradiol and 17α-hydroxyprogesterone by mass spectrometry. Five stages of gonadal maturation were observed. The hepatopancreas was formed by a set of tubules lined with pseudostratified epithelium composed of five cell types, cell E (undifferentiated), cell F (fibrillar), cell B (vesicular), R (reabsorbing), and M (basal) cells. Steroidogenic tissues were small in size and numerous. The ultrastructure of the ovary and hepatopancreas were studied during oocyte development. There was a high concentration of 17β-oestradiol and 17α-hydroxyprogesterone in stages I and II of ovarian maturation, coinciding with the preparation phase for vitellogenesis. A progressive decrease of these steroid hormones occurred during the course of gonadal maturation, and reached its lowest concentration in the spawning period. The ecdysone concentration did not fluctuate in ripe females. Its level increases from stages I-IV of vitellogenesis onward.

Biological Aspects of Waanders’s Hard-lipped Barbs (Osteochilus waandersii) in Tambatan River, North Sumatera, Indonesia

Background: Waanders’s hard-lipped barbs or scientifically known as Osteochilus waandersii belong to the family Cyprinidae with the potamodromous category. This fish can be found in the Tambatan river. It has the potential for commercial consumption or ornamental fish. Methods: This study was conducted in the Tambatan river from November to January 2021. The determination of three research stations was carried out using a purposive sampling method. Sampling was undertaken using cast nets. Furthermore, data analyzed were growth patterns, condition factors, and gonad maturity levels. Results: The growth patterns of male (1.944) and female (2.379) Osteochilus waandersii were in a negative allometric category. Besides, The Fulton's condition factor for male fish ranged from 0.42 - 3.43 with an average of 1.05, while that for female fish ranged from 0.59 - 3.67 with an average of 1.47. The result of the observation on the gonad maturity level for male and female O. waandersii in the Tambatan river indicated that they were dominated by fish with gonad maturity stage I (immature). Conclusions: Waanders’s hard-lipped barbs O. waandersii found were in the stage towards the mature level.

Stock status of Nile tilapia (Oreochromis niloticus) in Aneuk Laot Lake, Sabang District, Aceh Province, Indonesia

Abstract. Prianto E, Purwoko RM, Kasim K. 2021. Stock status of Nile tilapia (Oreochromis niloticus) in Aneuk Laot Lake, Sabang District, Aceh Province, Indonesia. Biodiversitas 22: 3364-3370. The Nile tilapia (Oreochromis niloticus) fishery in Aneuk Laot Lake plays a vital role in the local livelihoods. There is an indication of the massive exploitation of the species that potentially harm the stock and threaten its sustainability. This research aims to evaluate and assess the Nile Tilapia's stock status and use the results as baseline information to the management authorities. Surveys were conducted from May 2018 to April 2019 by collecting the length-weight data, sex, and gonadal maturity stage of 600 individuals. The Length-Based Spawning Potential Ratio (LB-SPR) was used to determine the Spawning Potential Ratio (SPR) and compared the results to the reference point. The results show that 50% of the females have matured at 15.1 cm, while the males at 17.8 cm. The individual fish length varies from 12.15 to 20.5 cm, whereas 50% of them were caught at size 17.8 cm (Lc50), meaning that predominantly of the fish had experienced first spawning before they were captured. The current SPR is about 5%, confirming the Nile tilapia's stock status is at an unhealthy state. Consequently, the precautionary approach, such as increasing the mesh size and limiting effort, should be considered to ensure the sustainability of the recruitment.

Процесс развития воспроизводительной системы у самцов осетровых рыб в индустриальных условиях на примере стерляди волжской популяции

The article describes special aspects of reproduction system development in male sturgeons using Volga sterlet population as an example (Acipenser ruthenus Linnaeus, 1758) within industrial enterprise of the Konakovskiy coarse fishery branch of the FSBSI Russian Federation Research Institute Of Fishery and Oceanography (VNIRO). The study results showed that gonad maturation stage I–II is completed at the age of 2 years if the total thermal constant is at least 11 thousand degree-days. Cytological sex differentiation occurs in the formed gland and begins at the age of three years if the thermal constant is more than 15 thousand degree-days. The onset of cytological differentiation can be determined by spermatogenesis waves characterised by intensive development of the male gonad III–VI maturity stages. Semelparity is typical for sturgeons, thus, the wave of spermatogenesis is seasonal, which indicates their limited participation in the spawning season at fish farms with natural water temperature. The knowledge of reproductive system development aspects in male sturgeons as illustrated by Volga sterlet population in the setting of industrial enterprise allows improving the practice of spermatogenesis process management at industrial farms ensuring the production of reproductive products of high fish-breeding quality at the time required for the enterprise. Considering the thermal constants made up by sterlet (males) spawners, it is possible to synchronise fish breeding processes (cycles) when receiving reproductive products from female sterlet and ensure repeated production of reproductive products from the same males in the settings of farms with controlled water temperature (throughout a calendar year). English version of the article is available at URL: https://panor.ru/articles/process-of-development-of-the-reproductive-system-in-male-sturgeon-in-industrial-conditions-on-the-example-of-the-sterlet-of-the-volga-population/68305.html

Activin receptor type IIB in rohu (Labeo rohita): molecular characterization, tissue distribution and immunohistochemical localization during different stages of gonadal maturation.

Activin receptor type IIB (ActRIIB) is a transmembrane serine/threonine kinase receptor which plays a pivotal role in regulating the reproduction in vertebrates including teleost. Earlier studies have documented its importance in governing gonadal maturation in higher vertebrates. However, reports on the regulation of fish reproductive system by ActRIIB gene are still limited. Here, we report the identification and characterization of ActRIIB cDNA of Labeo rohita, a commercially important fish species of the Indian subcontinent. The full-length gene encoding rohu ActRIIB was cloned and found to be of 1674bp in length. Functional similarities were evident from evolutionary analysis across vertebrates. Real-time PCR to measure the expression of ActRIIB transcript in rohu revealed significant mRNA levels in gonads followed by non-reproductive tissues, including the brain, pituitary and muscle. With respect to different gonadal maturation stages, predominant expression of ActRIIB mRNA was observed during the pre-spawning phase of both sexes. To further delineate its role in rohu reproduction, a recombinant protein of the extracellular domain of ActRIIB (rECD-ActRIIB) was produced, and polyclonal antibody is raised against the protein for its immuno-localization studies during different gonadal maturation stages. Strong immunoreactivity was noticed in the pre-vitellogenic oocytes which decreased dramatically in the fully mature oocytes. Similarly, the strong and intense immunoreactivity was found in the spermatids and spermatocytes of the immature testis, and eventually the intensity reduced with the progression of the maturation stage. These results provide the first evidence of the presence of ActRIIB in rohu gonadal tissues. Taken together, our observations lay the groundwork for further understanding and investigating on the potential role of ActRIIB in fish reproduction system in the event of gonadal maturation.

Effects of Diethylstilbestrol on Zebrafish Gonad Development and Endocrine Disruption Mechanism.

Environmental estrogen is a substance that functions as an endocrine hormone in organisms and can cause endocrine system disruption. A typical environmental estrogen, diethylstilbestrol (DES), can affect normal sexual function and organism development. However, even though the effects of different exposure stages of DES on the endocrine system and gonadal development of zebrafish juveniles are unknown, sex determination is strongly influenced by endocrine-disrupting chemicals (EDCs). From 10–90 days post fertilization (dpf), juvenile zebrafish were exposed to DES (100 and 1000 ng/L) in three different stages (initial development stage (IDS), 10–25 dpf; gonadal differentiation stage (GDS), 25–45 dpf and gonadal maturity stage (GMS), 45–60 dpf). Compared with that of IDS and GMS, the growth indicators (body length, body weight, and others) decreased significantly at GDS, and the proportion of zebrafish females exposed to 100 ng/L DES was significantly higher (by 59.65%) than that of the control; in addition, the zebrafish were biased towards female differentiation. The GDS is a critical period for sex differentiation. Our results show that exposure to environmental estrogen during the critical gonadal differentiation period not only affects the development of zebrafish, but also affects the population development.

A review of recent sightings and reports of the giant tiger shrimp <i>Penaeus monodon</i> (Decapoda: Penaeidae) on the Mexican coast of the Gulf of Mexico (2012-2019)

This work shows an update of the sightings and reports of tiger shrimp Penaeus monodon on the Mexican coast of the Gulf of Mexico recorded from 2012 to 2019 and reports the smallest specimen found in the western Atlantic. The results show an increase of almost 300% in sightings and reports since the first report. The zone with most sightings and reports was the coast of Campeche and Yucatán. The wide range of size and distribution of the captured specimens, including the smallest specimen found in the western Atlantic and the presence of females at an advanced stage of gonadal maturity, indicates that P. monodon has established itself in the area. The possible negative effects of such establishment make necessary the proposal of measures based on scientific evidence.

Determination of Some Biological Characteristics and Population Parameters of the Blotched Picarel (Spicara flexuosa Rafinesque, 1810) Distributed in the Eastern Black Sea (Rize - Hopa)

This study was carried out in order to determine some biological characteristics of the fish species of Spicara flexuosa, which is distributed on the Eastern Black Sea coast, and to contribute to the management of the picarel in all the seas of our country. Between October 2015 and September 2016, 599 fish samples were obtained and examined in the laboratory. It was determined that the examined individuals were distributed between the ages of I-VII which 31.22% of the population was male and 68.78% was female. The minimum-maximum total length values of the samples were between 8.7 and 21.8 cm; and the weight values ranged from 7.1 to 129.94 g. It has been determined that the mean total length of males is statistically different from that of females (P<0.05). Von Bertalanffy growth equilibrium was calculated as "L∞=22.71 cm TL, K=0.243 year-1, t0=-2.306 year-1; W∞=118.27 g" for females, "L∞=38.34 cm TL, K=0.063 year-1, t0 = -6.381 year-1; W∞=755.37 g" for males, and "L∞=33.42 cm TL, K=0.080 year-1, t0=-5.381 year-1; W∞=401.24 g" for all individuals. The length-weight relation of all individuals was found as W= 0.0118*L2.9727 (R2=0.9487). When the ratio of gonadosomatic index (GSI) data and gonadal maturity stages were examined over the year, it was determined that the reproduction of the picarel in the Black Sea occurred between June and September.

Morpho-meristics, maturity stages, GSI and gonadal hormone plasticity of African catfish Clarias gariepinus (Burchell 1822) that invaded into the Ganga River, India

BackgroundAfrican catfish Clarias gariepinus introduced to India has gravitated into the Ganga River as an invasive species. Morphological plasticity and reproductive adaptation are considered and reported as important manifestation contributing to evolution and persistence of an invasive species in the novel environment facilitating its expansion and establishment. African catfish in the Ganga River although documented to exist, it is yet to investigate if it elicits adaptation responses through morphological and reproductive plasticity in the riverine conditions. Therefore, morpho-meristic changes, plasticity in the reproductive stages, gonadosomatic index (GSI) and gonadal hormones were examined in C. gariepinus that invaded into the Ganga River so as to ascertain its invasion success.ResultsOut of 23 morpho-meristic characters examined, head length (HL), head depth (HD), anal fin length (AFL) and the pectoral fin rays (PECFR) were observed to differ significantly (p<0.05). The correlation coefficient ‘r’ between log length and log weight was found to be 0.9690 in culture and 0.8754 in river-caught specimens respectively. A distinct deviation in the maturity stages, GSI as well as gonadal hormones (testosterone, estradiol 17-β and vitellogenin) was further observed to change significantly in specimens of African catfish captured from the Ganga River as compared to those available in culture. Highest level of testosterone was found in males having gonadal stage V which was 184.82±10.4 pg/ml in culture and 204.82±21.34 pg/ml in river-captured specimens. The mean value of serum estradiol-17β was lowest (67.25±11.4 pg/ml) in gonadal maturity stage I and highest (328.73±24.5 pg/ml) in stage V in the river-captured C. gariepinus. The vitellogenin level in female C. gariepinus was detected in stage III, and it was maximum in stage V where it was 16.68±2.98 pg/ml in river-captured specimens and 12.63±2.12 pg/ml in cultured fish.ConclusionThe results of this study on morpho-meristic and gonadal plasticity provide first evidence of invasion success of the African catfish gravitated in the Ganga River which has now adapted to the river environments for breeding and establishing. The variations concerning different reproductive phases and the gonadal hormones in culture and river-caught C. gariepinus have been considered to contribute to the success of the colonisation and establishment. The knowledge generated on the phenotypic and reproductive plasticity of African catfish available in the Ganga River will help management and control programmes.

Dieta de Bryconamericus microcephalus (Characiformes, Characidae) em riachos da bacia do rio Cubatão (São Paulo, Brasil)

Analisamos a dieta de Bryconamericus microcephalus, espécie mais abundante nos riachos da bacia do rio Cubatão. Os exemplares foram coletados com pesca elétrica em 2016, em dez diferentes pontos da bacia, dentro da UC - Núcleo Itutinga-Pilões. Os peixes foram identificados, mensurados, pesados e dissecados. Estômagos com alimento foram retirados para análise da dieta pelo Grau de Preferência Alimentar. A dieta foi analisada através da relação do índice de diversidade de Shannon-Weaver e as características dos indivíduos. A relação entre os itens alimentares e o comprimento da espécie foi analisada por um teste de correlação de Pearson, e as relações dos itens qualitativos (sexo e os estádios de maturação gonadal) por uma Análise de Variância two-way. Foram amostrados 211 indivíduos, sendo 43 machos, 66 fêmeas e 102 imaturos. Analisamos 45 estômagos, nos quais registramos 20 itens, classificando a população estudada como onívora, com consumo principal de formas imaturas de insetos. O registro da maioria dos itens foi classificado como ocasional, refletindo o caráter oportunista da espécie, com consumo de itens de origem alóctone, evidenciando a forte relação com a mata ciliar. Ressaltamos assim, que a análise da dieta permite melhor compreensão da ecologia da espécie e sua conservação.

Reproductive Performance of Java Barb (Punctius javanicus) Injected sGNRH and Domperidone of Different Dosage

Java barb (P. javanicus) is freshwater fish frequently found in Java and Sumatra waters of Indonesia. Java Barb has a seasonal spawning cycle. Accordingly, the production of java barb seeds is limited by season. Therefore, it is necessary to research on hormonal manipulating systems of reproduction to needs of seeds. This study aimed to determine the effect of sGnRH and domperindone on Java barb reproductive performance. There were 12 female and 12 male java barb broodstock, with 400-500 grams and 300-400 grams bodyweight respectively. The broodstock used on third stage of gonadal maturation. This study used an experimental method with a completely randomized design (CRD) consisting of 4 treatments and 3 replicates. Mixture of GnRH and domperidone was injected intramuscularly. The dosage treatments used were dosage A (control), treatment B (0.3 ml/kg), treatment C (0.4 ml/kg) and treatment D (0.5 ml/kg). The data gathered included latency period, fertilization rate (FR), hatching rate (HR), survival rate (SR) and water quality. The results showed that the injection of sGnRH and domperidone produced different latency periods, significantly affected (P <0.05) fertilization rate (FR) and hatching rate (HR), but had no significant effect on survival (SR). The best results were obtained at treatment. B and treatment C with 0.3 ml/kg and 0,4 ml/kg dosage resulting in 9-12 hours latency period, 80,50±5,57 to 84.33 ± 5.51% of Fertilization Rate (FR), 68,83±6,81 to 71.17 ± 5.35% Hatching Rate (HR) and 53,85±2,35 to 60.69 ± 10.66% of Survival Rate (SR).