Fecundity Of Fish Research Articles

Effects of 5α-reductase inhibition by dutasteride on reproductive gene expression and hormonal responses in zebrafish embryos

Steroid 5α-reductase (SRD5A) is a crucial enzyme involved in steroid metabolism, primarily converting testosterone to dihydrotestosterone (DHT). Dutasteride, an inhibitor of SRD5A types 1 and 2, is widely used for treating benign prostatic hyperplasia. An adverse outcome pathway (AOP) has been documented wherein SRD5A inhibition decreases DHT synthesis, leading to reduced levels of 17β-estradiol (E2) and vitellogenin (VTG), subsequently impairing fecundity in fish (AOP 289). However, the molecular and cellular mechanisms underlying these effects remain poorly understood. In this study, we assessed the impact of SRD5A inhibition on zebrafish embryos (Danio rerio). Exposure to dutasteride resulted in decreased DHT, E2, and VTG levels, showing a positive correlation. Dutasteride also downregulated the expression of reproduction-related genes (srd5a2, cyp19a1, esr1, esr2a, esr2b, and vtg), with interrelated reductions observed across these levels. Docking studies suggested that dutasteride's effects may operate independently of androgen receptor (AR) and estrogen receptor (ER) interactions. Furthermore, co-exposure of dutasteride (0.5 or 2 μM) with 0.5 μM DHT revealed gene expression levels comparable to the control group. These findings underscore DHT's pivotal role in modulating estrogenic function and the interplay between estrogenic and androgenic responses in vertebrates. Our proposed AOP model offers insights into mechanistic gaps, thereby enhancing current understanding and bridging knowledge disparities.

A Quantitative Adverse Outcome Pathway for Embryonic Activation of the Aryl Hydrocarbon Receptor of Fishes by Polycyclic Aromatic Hydrocarbons Leading to Decreased Fecundity at Adulthood.

Quantitative adverse outcome pathways (qAOPs) describe the response-response relationships that link the magnitude and/or duration of chemical interaction with a specific molecular target to the probability and/or severity of the resulting apical-level toxicity of regulatory relevance. The present study developed the first qAOP for latent toxicities showing that early life exposure adversely affects health at adulthood. Specifically, a qAOP for embryonic activation of the aryl hydrocarbon receptor 2 (AHR2) of fishes by polycyclic aromatic hydrocarbons (PAHs) leading to decreased fecundity of females at adulthood was developed by building on existing qAOPs for (1) activation of the AHR leading to early life mortality in birds and fishes, and (2) inhibition of cytochrome P450 aromatase activity leading to decreased fecundity in fishes. Using zebrafish (Danio rerio) as a model species and benzo[a]pyrene as a model PAH, three linked quantitative relationships were developed: (1) plasma estrogen in adult females as a function of embryonic exposure, (2) plasma vitellogenin in adult females as a function of plasma estrogen, and (3) fecundity of adult females as a function of plasma vitellogenin. A fourth quantitative relationship was developed for early life mortality as a function of sensitivity to activation of the AHR2 in a standardized in vitro AHR transactivation assay to integrate toxic equivalence calculations that would allow prediction of effects of exposure to untested PAHs. The accuracy of the predictions from the resulting qAOP were evaluated using experimental data from zebrafish exposed as embryos to another PAH, benzo[k]fluoranthene. The qAOP developed in the present study demonstrates the potential of the AOP framework in enabling consideration of latent toxicities in quantitative ecological risk assessments and regulatory decision-making. Environ Toxicol Chem 2024;43:2145-2156. © 2024 SETAC.

Global patterns and drivers of fish reproductive potential on coral reefs

Fish fecundity scales hyperallometrically with body mass, meaning larger females produce disproportionately more eggs than smaller ones. We explore this relationship beyond the species-level to estimate the “reproductive potential” of 1633 coral reef sites distributed globally. We find that, at the site-level, reproductive potential scales hyperallometrically with assemblage biomass, but with a smaller median exponent than at the species-level. Across all families, modelled reproductive potential is greater in fully protected sites versus fished sites. This difference is most pronounced for the important fisheries family, Serranidae. When comparing a scenario where 30% of sites are randomly fully protected to a current protection scenario, we estimate an increase in the reproductive potential of all families, and particularly for Serranidae. Such results point to the possible ecological benefits of the 30 × 30 global conservation target and showcase management options to promote the sustainability of population replenishment.

A comprehensive study on biological parameters of Osteobrama cotio (Hamilton, 1822): Conservation strategy

Osteobrama cotio, commonly referred to as Dhela locally, is one of the most essential sources of nourishment for humans. The present study was conducted at the Freshwater Station of the Bangladesh Fisheries Research Institute in Mymensingh to learn more regarding the sex ratio, length-weight relationship, condition factor, gonadosomatic index, and fecundity. Fish samples were taken monthly, and their total length and weight were measured and noted. Among the 310 samples of fish evaluated, 201 (64.85%) and 109 (35.15%) were found to be females and males, respectively (F: M= 1.88: 1). The chi-square test findings showed that there was no statistically significant difference between the two sexes in the sex ratio study (χ2= 0.164, df= 1, p>0.05). It was shown that there was a substantial relationship (r2=0.76 for females, r2=0.96 for males, p<0.05) between fish fecundity and length. Positive allometric growth was observed in the length-weight relationships for both females and males (b=3.05 and 3.01, respectively; independent t-test; p<0.05). Throughout the study, the condition factor values for both sexes were more than 1, suggesting that both sexes are in excellent fitness (F=1.66 and M=1.67). Males and females showed GSI values ranging from 0.001 to 0.33 and 0.25 to 10.96, respectively. The gonadosomatic index scores for both sexes maximum in June while minimum in November. The range of fecundity was 297 to 6529; where June having the highest egg count, while November having the lowest.

Population Study of Kedukang Fish (Hexanematichthys sagor) in The Waters of Percut River, Percut Sei Tuan District, Deli Serdang Regency, North Sumatera

Kedukang fish (Hexanematichthys sagor) is a consumable fish that is widely caught by fishermen and the community. Kedukang fishing is carried out every day in the Percut River, resulting in a decline in its population. This study aims to analyze the population by looking at density, sex ratio, growth pattern, gonad maturity level, gonad maturity index and fecundity of kedukang fish and analyze the relationship between physical-chemical factors of waters with population density of Kedukang fish. Samples were taken using purposive sampling method at 3 observation stations with 2 repetitions. Fish samples were taken using a net fishing gear installed at low tide and lifted at high tide. The results showed that the population density of kedukang fish in Percut River was low ranging from 0.048-0.123 ind/m2. The sex ratio kedukang fish at each observation station has an average of 1:0.5. The growth pattern of fish is allometric negative. The frequency distribution of fish length ranged from 21.5-47.9 cm. The greatest number of fish caught had a length range of 30.3-34.7 cm as many as 9 fish. The level of gonad maturity kedukang fish is dominated by TKG V. The average gonad maturity index of female kedukang fish is highest at the TPI location which is 20.729% and the highest fecundity at station II which is 4622.6. The relationship between the density of the kedukang fish population is very strong and positively correlated with DO, light intensity and nitrate. The population density of kedukang fish was strongly and negatively correlated with pH and phosphate.

Japanese medaka (Oryzias latipes) exposed via maternal transfer to the brominated flame retardant, 1,2,5,6-tetrabromocyclooctane (TBCO), experience decreased fecundity and impaired oocyte maturation

Early life-stage exposure of fishes to endocrine disrupting chemicals can induce reproductive impairment at sexual maturity. Previously, we demonstrated decreased fecundity of Japanese medaka (Oryzias latipes) exposed via maternal transfer to the novel brominated flame retardant, 1,2,5,6-tetrabromocyclooctane (TBCO). However, that study failed to identify the causative mechanism. In other studies we have shown that decreased fecundity of adult fish exposed to dietary TBCO is likely due to impaired oocyte maturation. The goal of the present study was to determine if impaired oocyte maturation is responsible for decreased fecundity of Japanese medaka exposed as embryos to TBCO, via maternal transfer. Sexually mature fish (F0) were fed either a control diet or a low (74.7 μg/g) or high (663 μg/g) diet containing TBCO for 21 days. Eggs (F1) were collected during the final week of exposure and reared to sexual maturity at which point fecundity was assessed using a 21-day reproduction assay. Upon termination of the assay, an ex vivo oocyte maturation assay was used to determine whether maturation inducing hormone (MIH) stimulated oocyte maturation was impaired. Additionally, concentrations of 17β -estradiol (E2) in blood plasma and expression of genes involved in vitellogenesis and oocyte maturation were quantified. The F1 generation females reared from the low or high F0 treatments experienced a 26.0 % and 56.8 % decrease in cumulative fecundity, respectively. Ex vivo MIH stimulated oocyte maturation from the low and high TBCO treatments were decreased by 23.4 % and 20.0 % respectively. There was no significant effect on concentrations of E2. Transcript abundance of vtgI was significantly decreased in a concentration dependent manner. Transcript abundance of mPRα, pgrmc1, pgrmc2, and igf3 were decreased but effects were not statistically significant. Overall, results suggest that impaired oocyte maturation causes decreased fecundity of Japanese medaka exposed to maternally deposited TBCO.

MSCF: Multi-Scale Canny Filter to Recognize Cells in Microscopic Images

Fish fecundity is one of the most relevant parameters for the estimation of the reproductive potential of fish stocks, used to assess the stock status to guarantee sustainable fisheries management. Fecundity is the number of matured eggs that each female fish can spawn each year. The stereological method is the most accurate technique to estimate fecundity using histological images of fish ovaries, in which matured oocytes must be measured and counted. A new segmentation technique, named the multi-scale Canny filter (MSCF), is proposed to recognize the boundaries of cells (oocytes), based on the Canny edge detector. Our results show the superior performance of MSCF on five fish species compared to five other state-of-the-art segmentation methods. It provides the highest F1 score in four out of five fish species, with values between 70% and 80%, and the highest percentage of correctly recognized cells, between 52% and 64%. This type of research aids in the promotion of sustainable fisheries management and conservation efforts, decreases research’s environmental impact and gives important insights into the health of fish populations and marine ecosystems.

Impairment of oocyte maturation as a mechanism of decreased fecundity in Japanese medaka (Oryzias latipes) exposed to the brominated flame retardant, 1,2,5,6-tetrabromocyclooctane (TBCO)

Inhibition of oocyte maturation is an understudied mechanism by which chemical stressors can impair fecundity of female fishes. The primary objective of the present study was to develop an assay to assess oocyte maturation disruption by chemical stressors in Japanese medaka (Oryzias latipes). First, an in vitro assay to assess maturation inducing hormone (MIH)-stimulated oocyte maturation in zebrafish was validated for use with Japanese medaka. Next, using the brominated flame retardant, 1,2,5,6-tetrabromocyclooctane (TBCO), which previously was shown to decrease fecundity of Japanese medaka and inhibit oocyte maturation in zebrafish, effects on oocyte maturation were quantified using in vitro and in vivo exposure. Adaptation of the protocol for in vitro MIH-stimulated maturation of stage IV oocytes from zebrafish was successful in inducing greater than 80% of stage IX oocytes from female Japanese medaka to mature. To assess effects of in vitro exposure, stage IX oocytes were exposed to 0, 2, 20, and 200 μg/L of TBCO, followed by exposure to MIH. The in vitro exposure caused a significant decrease in maturation of oocytes exposed to 20 and 200 μg/L of TBCO. To assess effects of TBCO on fecundity and oocyte maturation following in vivo exposure, sexually mature fish were fed a control, 100 μg/g, or 1000 μg/g concentration of TBCO-spiked fish food for 21 days, where fecundity was measured daily, and following the exposure, stage IX oocytes were excised to assess MIH-stimulated maturation. Fecundity and oocyte maturation were significantly decreased at either concentration of TBCO. Plasma concentrations of 17β-estradiol (E2) and hepatic abundances of transcripts of vitellogenin (vtgI and vtgII) were quantified, but there were no significant differences between treatments. Results suggest that inhibition of oocyte maturation is a mechanism by which TBCO decreases fecundity, and that in vitro assays of oocyte maturation might be predictive of fecundity in this species.

Structure of the spawning herd and stocks of the Siberian vendace of the Yenisei River

The aim of the research is to evaluate the structural and biological parameters of the spawning stock of the turukhanskaya form of the Siberian vendace Coregonus sardinella (Valenciennes, 1848) from the Yenisei River and the state of the commercial stock of this fish species in the period from 2014 to 2021. Research methods: in the research used the ichthyological material collected in the period from 2014 to 2021 in the lower reaches of the Yenisei River (near the Dudinka town and the village of Levinsky Sands). Processing of ichthyological materials was carried out according to generally accepted methods. The number of spawning herds of Siberian vendace was calculated using a virtual population analysis in Galland’s modification. Instant natural mortality rates by age groups were calculated using the method of L. A. Zykov. Results: According to the control catches, the age of the spawning stock of the turukhanskaya form of Siberian vendace in the Yenisei River was 2+–9+ years. Fish aged 4+ years, which in different years constituted from 47 to 68 % of the spawning stock, dominated in the population. The average long-term age of the spawning population in the study period was 4.2 years. The ratio of females and males in the spawning herd was close to 1:1 on average. Individual absolute fecundity of fishes varied in the range from 1.9 to 12.5 thousand eggs, increasing with increasing age and size of females. The average population fecundity is 2.6–5.3 thousand eggs. The number and biomass of the spawning herd in different years varied from 11.0 to 30.5 thousand individuals and from 630 to 1738 tons, respectively. Practical significance: the obtained results about the dynamics and structure of the spawning stock of the semi-anadromous form of the Siberian vendace from Yenisei River for the period from 2014 to 2021 will be used for prognostic purposes in the preparation of materials substantiating the volumes of the recommended catch in the basin of the Yenisei River. Conclusion: Based on the results of the analysis of the age, size-weight and sex structure, it was shown that the state of stocks of the semi-anadromous turukhanskaya form of the Siberian vendace in the Yenisei River is currently in a satisfactory condition.

Global expression pattern of genes containing positively selected sites in European anchovy (Engraulis encrasicolus L.) may shed light on teleost reproduction.

European anchovy is a multiple-spawning and highly fecundate pelagic fish with high economic and ecological significance. Although fecundity is influenced by nutrition, temperature and weight of spawners, high reproductive capacity is related to molecular processes in the ovary. The ovary is an essential and complex reproductive organ composed of various somatic and germ cells, which interact to facilitate the development of the ovary and functional oocytes. Revealing the ovarian transcriptome profile of highly fecundate fishes provides insights into oocyte production in teleosts. Here we use a comprehensive tissue-specific RNA sequencing which yielded 102.3 billion clean bases to analyze the transcriptional profiles of the ovary compared with other organs (liver, kidney, ovary, testis, fin, cauda and gill) and juvenile tissues of European anchovy. We conducted a comparative transcriptome and positive selection analysis of seven teleost species with varying fecundity rates to identify genes potentially involved in oogenesis and oocyte development. Of the 2,272 single copies of orthologous genes found, up to 535 genes were under positive selection in European anchovy and these genes are associated with a wide spectrum of cellular and molecular functions, with enrichments such as RNA methylation and modification, ribosome biogenesis, DNA repair, cell cycle processing and peptide/amide biosynthesis. Of the 535 positively selected genes, 55 were upregulated, and 45 were downregulated in the ovary, most of which were related to RNA and DNA transferase, developmental transcription factors, protein kinases and replication factors. Overall, our analysis of the transcriptome level in the ovarian tissue of a teleost will provide further insights into molecular processes and deepen our genetic understanding of egg production in highly fecund fish.

Respons Ekstrak Hipofisa Kambing Terhadap Fekunditas Ikan Betok (Anabas testudineus)

The production of betok fish has experienced overfishing and resulted in a decrease in productivity, therefore one of the efforts made to help success in spawning betok fish can be done by stimulating factors related to the reproductive system, namely by stimulating the work of hormones in stimulating gonadal maturation in artificial spawning with hypophysation method. This study aims to look at the response of goat pituitary extract to the fecundity of betok fish (A. testudineus, Bloch). This research was conducted for 30 days, using 4 treatments with 3 replications, with details of treatment P0: Control, treatment P1: Goat Pituitary Extract 0.05 ml/kg, Treatment P2: Goat Pituitary Extract 0.2 ml/kg, and treatment P3 : Goat Pituitary Extract 0.35 ml/kg. The results of the study using the best goat pituitary extract in the P2 treatment (0.2 ml/kg Goat Pituitary Extract) produced the highest fecundity, namely 8349 eggs produced. The results of water quality measurements showed that the pH value was 7.6 – 7.7. water temperature is 270C – 300C, dissolved oxygen (DO) is 2.9 – 4.4 mg/L. and the content of ammonia (NH3) during the study was 0.012 – 0.013 mg/L.

Effect of Differences in Betta Fish (Betta Splendes) Strains on Fecundity, Fertility, Egg Diameter and Hatchability

Betta fish (Betta splendens) has export and import potential. Several popular betta fish strains include halfmoon, crown tail, double tail, and placard. We used the observation method to observe four betta fish strains with five replications. The four fish strains were spawned and will be dissected to obtain the female betta fish's gonads. The parameters observed in this study were fecundity, egg diameter, fertility, and hatchability. This study's data analysis method was analysis of variance (ANOVA) with Duncan's multiple range test. Based on the findings of the observations, it is known that the results of betta fish spawning and gonadal dissection on these various betta fish strains show a significant difference in fish fecundity (P 0.05). However, no significant difference in egg diameter, fertility, or hatchability was observed (P > 0.05). Betta splendes strains differ in terms of fecundity, fertility, hatching rate, and egg size.

Full sexual maturity-cycle exposure to environmentally relevant concentrations of 17β-estradiol decreases reproductive capacity of zebrafish

17β-Estradiol (E2) has been widely detected in natural water and treatment with E2 induces potential endocrine disrupting effects in fish. However, effects on fish fecundity and steroid system after treatment with environmentally relevant concentrations of E2 for the full sexual maturation cycle remain unclear. In this study, zebrafish were treatment with 0, 10 or 100 ng/L E2 from embryo to adult stage, and effects on gonadal development and differentiation, steroid hormone levels, transcription of genes associated with the hypothalamic-pituitary-gonadal-liver (HPG) axis in adults and fertilization rate of offspring were assessed. The results showed that treatment with E2 lead to increased number of feminization in zebrafish. In females, E2 decreased cumulative amount of spawning and inhibited the maturation of oocyte. In males, E2 inhibited the maturation and motility of sperm, as well as decreased the movement speed of sperm. These adverse effects on sperm might be responsible for the reduced fertilization observed in offspring. In addition, treatment with E2 changed the levels of steroid hormones in zebrafish gonad and altered the transcriptional levels of genes associated with HPG axis, which is responsible for the regulation of germ cells maturation and gonadal development in zebrafish. Overall, these results suggested that treatment with environmentally relevant concentrations of E2 for the full sexual maturity cycle resulted in adverse effects on reproduction in zebrafish.

Reproductive biology of Indian mackerel, Rastrelliger kanagurta (Cuvier, 1816) in the southern waters of West Java (FMA 573)

Indian mackerel is a small pelagic fish with important economic value in Java Island. This study aims to analyze the reproductive characteristics and determine management recommendations for the Indian mackerel in the southern waters of West Java. Fish monthly sampling collection was conducted at three fish landing ports: PPI Ciwaru, PPN Palabuhanratu, and PPI Binuangeun from July to December 2022. A total of 1,038 fish samples, comprised of 582 males and 456 females, were examined. The sex ratio was unbalanced, with a value of 1:0.79. Gonadosomatic indexes ranged from 0.19-0.95 and 0.45-3.41 for males and females, respectively. The fish fecundity ranged from 27,027 to 87,837 eggs. The Indian mackerel is predicted to spawn every month, with a peak season in August, and performs a total spawner pattern. The Indian mackerel reached the size of the first maturity gonad at 198.5 mm and 197 mm for males and females, respectively. Management strategies for Indian mackerel in the southern waters of West Java include setting the catch size above the first mature gonad size (197 mm), the mesh size of gillnets above 1.5 inches, and limiting fishing activities during the spawning season (July, August, and September).

Fecundity of Glyptothorax telchitta (Hamilton, 1822) from Tamor River, Nepal

The present study assesses the fecundity of Glyptothorax telchitta, a hill stream fish from the Tamor River, Nepal. A total of 60 specimens were collected from the Tamor River, with the help of local fishermen between March 2019 and February 2020. The absolute fecundity ranged from 3385 to 14298 eggs with the mean absolute fecundity of 9448.469 ± 607.783. The fish was found to be a medium fecund fish. Relative fecundity ranged from 151 to 529 eggs per gram body weight with mean relative fecundity of 371.38 ± 15.72. Fecundity showed significant positive correlations with ovary weight (r = 0.858) total length (r = 0.844) and total weight (r = 0.825). This indicated that fecundity dependent is mostly on ovary weight. Gonado-somatic index scored the peak values during March (15.15%) and May (15.01%), indicating the fish’s spawning period during the spring season. Egg sizes varied from 0.382 mm to 1.149 mm. The appearance of various sizes of eggs in a single ovary indicated that the fish was a fractional spawner. The ovaries occupied maximum space in the abdomen during the breeding season.

Some Aspects of the Reproductive of Japanese Threadfin Bream (Nemipterus japonicus Bloch, 1791) Caught in the Area Around the Artificial Reef In the Pitu Sunggu Waters of the Makassar Strait

Japanese Threadfin Bream is a demersal fish commonly found around artificial reefs. Food availability in the artificial reef ecosystem is essential for the sustainability of this species. Hence, this research aimed to determine several aspects of bio-reproduction of Japanese Threadfin Bream caught in the artificial reef (bioreeftek). Samples were taken using handline fishing, twice a month (April-July 2020) in Pitu Sunggu Waters, Makassar Strait. The samples were observed for its reproduction aspects. The result showed that the Japanese Threadfin Bream fish caught have a balanced sex ratio between males and females, 1:1.03. The analysis of the gonad maturity stage obtained was II-IV, and the gonado somatic index ranged from 0.541-0.940 for males and 1.156-2.358 for females. The first mature Japanese Threadfin Bream size was 18.29 cm for males and 16.99 cm for females. The Japanese Threadfin Bream fish fecundity ranged between 35.042-42.061 eggs.

Effect of Different Doses of Pituitary Gland (PG) Hormone on Induced Breeding of Bheda/Meni (Nandus nandus) Fish

An experiment on induced breeding of Bheda/Meni fish (Nandus nandus) was carried out to determine the optimum dose of pituitary gland hormone during December 2018 to June 2019 at Floodplain Sub-station of Bangladesh Fisheries Research Institute (BFRI), Santahar, Bogura. In this experiment, PG was used as inducing agent for both male and female fish. For induced breeding, PG was administered at the rate of 1, 2 and 3 mg/kg body weight to male brood fish, and correspondingly 2, 4 and 6 mg/kg body weight to female brood fish that were considered as the treatments namely, T1, T2 and T3, respectively. Fifty pairs of male and female fish were collected from the Raktadaha beel from where forty-five pairs were selected for induced breeding and the average body weight of the male and female were 43.0±2.5 gm and 55.2±3.0 gm in T1, 45.1±2.9 gm and 56.0±2.8 gm in T2, and 40.3±2.4 gm and 52.6±3.2 gm in T3. The male-female ratio was maintained as 1:1 in the breeding hapa. It was observed that female and male brood fishes ejected eggs and milt, respectively at the contemporary times. Ovulation occurs naturally after 8-10 hours of injection. The fecundity of fish (body weight 45 to 60 gram each) varied from 7,232-27,546. The fertilized eggs were hatched within 16-20 hours. The hatchlings were reared in rearing tank up to 5 days. The fertilization rate of Nandus nandus were 76±4 %, 93±5 % and 57±3 %, in T1, T2, and T3, respectively and the hatching rate were 72±3 %, 86±2 % and 61±4 % in T1,T2 and T3, respectively. Both the fertilization and hatching rates were significantly higher (p<0.05) in T2 treatment than T1 treatment followed by T3 treatment. The mean values of water temperature (°C) were 29.5±1.15, 30.0±2.03 and 30.8±1.76°C, pH was 7.4 ±0.46, 7.8±0.53 and 7.3±0.49 and dissolved oxygen (mg/L) were 5.5±0.61, 5.3±0.24 and 5.8±0.56 in brooder tanks, breeding hapa and larval hapa, respectively during the experiment and did not vary (P>0.05) among them and were suitable for induced spawning of Nandus nandus. Based on the findings of the present experiment, it was revealed that T2 showed the best outcome in terms of fertilization rate (93±5%) and hatching rate (86±2%) among the three treatments under optimum water quality parameters where PG hormone were used at the rate of 2 and 4 mg/kg body weight for male and female fish, respectively. Therefore, the present findings could be used in induced breeding of N. nandus for the development of hatchery propagation. Further trials on rearing or culture of this endangered fish under different stocking densities or feedings might be conducted at on-station and on-farm levels in Bangladesh as well as elsewhere of this region to save the fish from extinction or for its conservation and rehabilitation.

The Effect of Parental Length and Weight on Fecundity of Betta sp.

Betta fish is a fish that has a high economic value, Market demand always increasing. However, to get high Quality betta fish, efforts are still needed by importing from Singapore and Thailand so that a sustainable betta fish hatchery business is needed. To develop this betta fish hatchery business, the first thing that must be considered is the value of fecundity. Fecundity plays an important role in supporting the success of fish growth. This study aims to determine the relationship between the length and weight of betta fish broodstock to the value of fecundity as an effort to develop in the field of aquaculture, especially at the hatchery stage. The method used in this research is Descriptive method which is then analyzed using linear regression, namely the relationship between length and weight on the fecundity of betta fish. The data is presented in the form of tables and graphs which are then analyzed descriptively to draw conclusions from the resulting data. In this study, 30 brood betta fish were used with body weights ranging from 1.39 to 1.73gr and lengths of 4.5 to 5.2cm and the resulting fecundity ranged from 166 to 366 eggs. The results showed that fecundity had a close relationship with fish body weight where the correlation coefficient (r) was 0.9653 and the coefficient of determination (R²) was 0.9319. While the long relationship with fecundity has a moderate relationship where the correlation coefficient (r) obtained is 0.4079 and the coefficient of determination (R²) is 0.1664. This indicates that fish weight is better used to estimate the value of fish fecundity than body length. Keyword: Betta fish, Fecundity, Body weight, Body length

Effects of environmental enrichments on ovarian development of Buitta Catfish (Sperata sp.: Family Bagridae) in captivity

Environmental enrichment (EE) is an important factor that helps improve both the physical and psychological behavior of farmed animals. This factor also controls social interactions and provides more stimulants to influence the reproductive performance of animals in captivity. As EE plays an important role in animal reproduction, the present study was designed to investigate the effects of different types of tank bottom enrichments on the ovarian development of Buitta (Sperata sp.) catfish in captivity. Barren (TA), muddy (TB), and sandy (TC) enrichments were utilized for four months to observe the physical and psychological changes of the catfish. The results showed significant differences (p < 0.05) in the weight gain, gonadosomatic index (GSI), and hepatosomatic index (HSI) of the fish, however, no significant difference was found in the fish fecundity. The most prominent changes include weight, ripeness, the biochemical composition of body tissues, and the frequency distribution of the migratory nucleus in the oocytes. Moreover, the diameter of oocytes that occurred in the enrichment TC (p < 0.05) was significantly higher than the enrichments TA and TB. Histological observation found at least two stages of the ovarian oocytes development process in each ovary indicating the asynchronous self-reproduction of the fish. Additionally, biological macromolecules analysis found higher protein content in the muscle (86.04%), liver (52.97%), and oocyte (64.71%) and a higher deposition of lipid within the oocytes (32.33%) and liver (27.06%) for enrichment TC, while these values were lower for the other two treatments. Finally, the study suggests that a sandy environment should be used to obtain an acceptable level of oocyte development in the female Buitta fish in captivity.

Modern commercial and biological characteristics of zander Sander lucioperca (L) of the Kuibyshev reservoir

The article presents the research materials of pike perch r. Volga and the Kuibyshev reservoir and noted the changes that have occurred in its population. Prior to the creation of the reservoir in the conditions of the Middle Volga, male zander matured at the age of 5–6 years, females at 6–7 years. In the Kuibyshev reservoir, pike perch becomes sexually mature at the age of 4–5 years, and a small part of it matures at the age of three. In the reservoir, due to ecological plasticity and the ability to lay eggs in a wide temperature range, regardless of the level regime of the reservoir and the spawning substrate, a gradual increase in its biological indicators, abundance and reserves began to be noted. Improving the feeding conditions of zander in the reservoir contributed to earlier puberty, an increase in the absolute fecundity of fish and its abundance in the reservoir. This contributed to an increase in zander catches since 1974, which in 1985 reached a maximum of 517 tons (9,2% of the total fish catch in the reservoir). Sufficiently high catches of zander over the past 10–15 years indicate the stability of its stocks in the Kuibyshev reservoir, which currently tend to increase. The multi-age sizeweight composition of zander in the Kuibyshev reservoir is represented by both young and older individuals, and confirms that the population is in good condition.