Fish Reproduction Research Articles

Addition of Bean Sprout Extract (Vigna radiata) in Feed for Rematuration of Female Tilapia Fish (Oreochromis niloticus)

The availability of protein, vitamins, minerals and calcium in feed are also very important in the process of gonad development of tilapia. This research aims to examine the reproduction of tilapia fish that add bean sprout extract to feed at different doses. Addition of bean sprout extract to feed at different doses for rematuring female tilapia fish that are kept for 18 days. The feed used in the research was CPP floating feed with a protein content of 31%, mixed with bean sprout extract according to the treatment: A (control without bean sprout extract), B (10% bean sprout extract), C (30% bean sprout extract), and D (50 % bean sprout extract). Data were analyzed based on the parameters of gonad maturity level, gonad maturity index, and fecundity. Gonad maturity level IV, ready to spawn. Bean sprout extract did not have a significant effect on the gonad maturity index, with the highest gonad maturity index at a dose of 10% (3.96%) compared to the control (3.29%). The highest fecundity was also found at a dose of 10% (3,380 grains), decreasing at higher doses, but still higher than the control (1,824 grains). The addition of bean sprout extract increased fecundity but did not significantly affect the gonad maturity index. Keywords: Tilapia, Feed, Bean Sprouts, Rematuration

Toxic effects of microplastic and nanoplastic on the reproduction of teleost fish in aquatic environments.

Microplastics and nanoplastics are widely present in aquatic environments and attract significant scholarly attention due to their toxicity, persistence, and ability to cross biological barriers, which pose substantial risks to various fish species. Microplastics and nanoplastics can enter fish through their digestive tract, gills and skin, causing oxidative damage to the body and adversely affecting their reproductive system. Given that fish constitute a crucial source of high-quality protein for humans, it is necessary to study the impact of microplastics on fish reproduction in order to assess the impact of pollutants on ecology, biodiversity conservation, environmental sustainability, and endocrine disruption. This review explores the reproductive consequences of microplastics and nanoplastics in fish, examining aspects such as fecundity, abnormal offspring, circadian rhythm, gonad index, spermatocyte development, oocyte development, sperm quality, ovarian development, and changes at the molecular and cellular level. These investigations hold significant importance in environmental toxicology.

Conditions for reproduction of juvenile salmon fish in Sakhalin fish hatcheries: oxygen, temperature regimes and sanitary state of factory water sources

Conditions for reproduction of juvenile salmon fish in Sakhalin fish hatcheries: oxygen, temperature regimes and sanitary state of factory water sources

A novel approach for rapidly determining the reproductive status of walleye pollock (Gadus chalcogrammus) using Raman spectroscopy

Knowledge of the reproductive biology of fishes is essential for effective fisheries management. Information derived from an understanding of fish reproduction, such as size and age at maturity, is used in models to assess fish stocks and can affect estimates of important ecological processes such as recruitment, abundance, and trophic interactions. Common practices for determining the reproductive status of teleost fishes include macroscopic evaluation of gonads as well as histological analysis. However, macroscopic evaluation can be biased and histological analysis is time-consuming, resulting in limitations to spatial and temporal data availability. Here, we explore Raman spectroscopy of ovaries as a novel approach to rapidly determine the reproductive status of walleye pollock (Gadus chalcogrammus), a commercially and ecologically important species in the North Pacific. We used a two-stage partial least-squares (PLS) regression analysis followed by a linear discriminant analysis (LDA) to classify walleye pollock ovary samples as physiologically mature or immature and to subsequently predict their histologically-determined reproductive stage based on the Raman spectra. Biologically mature samples with visible yolk differentiated from mature and immature samples (non-yolked; 99% accuracy). Non-yolked ovaries that were physiologically mature (either mature non-developing or previously spawned) were further differentiated from physiologically immature ovaries (93% accuracy). In addition, detailed, histologically-determined reproductive stages of yolked samples also differentiated via Raman spectroscopy, but with reduced accuracy (79% - 86% accuracy). Our results indicate that accurate identification of maturity status and the reproductive staging of oocytes of walleye pollock based on spectral data from ovaries is possible. This can provide a fast and efficient way to increase the availability of a key component of reproductive data to inform fisheries research and management.

The effect of cortisone on female zebrafish (Dania rerio): Reducing reproductive capacity and offspring survival rate

Cortisone is a naturally occurring corticosteroid hormone known for its wide range of anti-inflammatory and immunosuppressive effects, and it is commonly found in various aquatic environments. Previous reports have shown that cortisone can have significant negative impacts on fish; however, its specific effects on fish reproduction have not been thoroughly investigated. In this study, female adult zebrafish were exposed to 0.0 (control), 3.9, 40.2, and 377.9 ng/L of cortisone for 60 days, and multiple endpoints were evaluated. The results showed that as the concentration of cortisone increased, there was an increase in the percentage of perinuclear oocytes and a decrease in the proportion of late-stage oocytes, indicating a stagnation in oocyte development. Additionally, female zebrafish exposed to cortisone exhibited decreased attraction to males and reduced mating intimacy. Furthermore, exposure to cortisone resulted in changes in the development and behavior of zebrafish embryos. At cortisone concentrations of 3.9 and 40.2 ng/L, fewer eggs were laid and the survival rate of fertilized eggs decreased. These observed effects are associated with abnormal transcription levels of genes (Star, Cyp11a1, Cyp17, Cyp19a, Cyp11b, Hsd11β2, Hsd17β3) related to the HPG axis. These findings provided new insights into understanding potential environmental risks associated with corticosteroids.

Pesticides and Heavy Metal Toxicity in Fish and Possible Remediation – A Review

Abstract Pesticides and heavy metals are considered as potent contaminants in aquatic environment. Both contaminants are sourced into the aquatic ecosystems by various types of anthropogenic as well as natural practices. Such types of aquatic contamination drastically affect the normal activity of associated living organisms particularly fish. Both the pesticides and heavy metals toxicity cause several negative effects on fish growth, physiology, immune response, reproduction, embryonic and larval development as well as different histopathology of major organs including fish gill, kidney, liver, gonads, and intestine. Besides, the consumption of contaminated fish poses a serious health concern to associated consumers. Considering these serious issues, the current review is designed to investigate the toxic effects of pesticides and heavy metals on different aspects of fishes along with their possible sources, major types, and mode of action as well as role of medicinal herbs to mitigate their toxicity.

The association of certain lipid metabolism indicators and light regimes in salmonids and cyprinids in aquaculture

Purpose of the review: analysis of the effect of the photoperiodic factor based on indicators of lipid metabolism in Salmonid and Cyprinid fish species.Methods used: comparative analysis of literature and own experimental data.Results: The length of daylight (photoperiod) is one of the most important abiotic factors affecting the behavior, reproduction, metabolism, growth and development of fish. The changes in the lipids and fatty acid constituents execute a significant role in the adaptation of aquatic organisms to new light conditions. Certain parameters of lipidogenesis can serve as a reliable indicator of the normal route of metabolic processes in the organism. It is widely known that photoperiod regimes are used in aquaculture to optimize the cultivation of various species of aquatic organisms, including the most common Cyprinids and Salmonids. The specificity of the reaction of lipid metabolism to the effects of various lighting modes is shown: in cyprinids, the reaction can be multidirectional depending on the species (including its absence), while in Salmonids on example of Atlantic salmon, a change in the lipid profile in the direction of smoltification is observed. The role of combining the photoperiod with other factors, such as feeding and climatic features of the region, are discussed.Significance: The results can contribute to a better understanding of the adaptive processes in fish and optimize the conditions for their artificial rearing.

The seasonal rate of discharge change as the primary trigger synchronizing freshwater fish reproduction in an Amazonian River

The seasonal rate of discharge change as the primary trigger synchronizing freshwater fish reproduction in an Amazonian River

Prediction of outflow temperature of reservoir based on theory-guided machine learning models and optimization of operation for improving outflow temperature

The proportion of hydropower within the energy-resource structure is gradually increasing. However, the construction of reservoirs inevitably leads to ecological and environmental issues, especially the release of low-temperature water in summer and its detrimental effects on fish spawning and reproduction. These issues can be alleviated by optimizing the reservoir operation scheme, but the large amount of time required for predicting the reservoir outflow temperature emerges as the primary constraint. In this study, we considered Pubugou (PBG) Reservoir and proposed an efficient and high-precision prediction method for reservoir outflow temperature based on theory-guided machine learning (TGML) algorithms. This method was applied to the multi-objective optimization of the reservoir operations, and an optimization operation plan was proposed to improve the outflow temperature. The research results indicate that the LightGBM machine learning model shows good predictive performance, with a maximum deviation of no more than 1 °C in predicting the outflow temperature. There is a significant competitive relationship between reservoir power generation and the outflow temperature. Compared with the current operational scheme, the maximum power operation plan results in a 4.4% increase in total power generation but causes the average outflow temperature during the fish spawning period to decrease by 0.1 °C. The total power generation of the improved outflow temperature operation scheme was 0.8% lower than that of the actual scheme, but the average outflow temperature during fish spawning increased by 0.2 °C. Properly increasing the discharge flow from the reservoir and lowering the water level can thus help alleviate the issue of outflow temperature.

Transcriptomic Analysis of the Effects of Changes in Temperature and Flow Velocity on Reproductive Ability of Coreius guichenoti

ABSTRACTThe establishment of reservoirs, which alter water temperature and flow dynamics, significantly affects the indigenous fish population, yet the underlying molecular mechanisms remain unclear. To investigate effects of the changing water temperature and flow rate on fish ovaries, we subjected female Coreius guichenoti to the combination of different water temperatures (17°C, 20°C and 23°C denoted as L, N and H, respectively) and flow velocities (0 and 0.5 m/s denoted as S and V, respectively). After 30‐day experiment period, we identified 393, 545, 300 and 657 differentially expressed transcripts in HV versus NV, LV versus NV, HS versus NV and LS versus NV, respectively. The transcriptome results showed that both environmental factors could significantly influence oogenesis, with water temperature exerting a more pronounced effect than flow velocity. In particular, the higher temperature (HV and HS) led to a tendency towards masculinization and even infertility in females, which were consistent with the histopathology results. By contrast, the lower temperature (LV and LS) promoted the progression of desirable female attributes, where static water conditions (LS) had a greater effect compared with flowing water (LV). These findings were of great significance for the adaptive operation of reservoirs to create reasonable and precise ecological flows for managing fish reproduction.

Optimal balance of organic detritus and feed for fish growth and water quality improvement through regulating nutrients cycling

In order to explore the effects of different feed composition on the nutrient level and microbial loop structure in aquaculture ponds, a field simulation experiment in aquaculture ponds was conducted by adding different proportions (0%, 20%, 40% and 60%) of bagasse to fish feed for combined feeding. The addition of bagasse significantly reduced the levels of various forms of nitrogen and phosphorus in the water, especially with the addition of 60% bagasse. In the treatments without addition and with 20% bagasse added, nitrogen and phosphorus levels remained relatively high, which should be attributed to the decomposition of feed and the release of sediment, ultimately stimulating the abundant reproduction of algae. Bacterial growth was limited due to insufficient supply of organic carbon, and the growth of fish relied more on the components of the feed. With the addition of 60% bagasse, the high organic carbon and low nitrogen and phosphorus levels could not support the growth of phytoplankton, bacteria, and zooplankton. It is inferred that organic carbon may be more degraded into carbon dioxide, ultimately limiting the growth of fish. Adding 40% bagasse achieved a balanced level of carbon, nitrogen, and phosphorus, establishing a healthy and stable microbial loop structure (including phytoplankton, bacteria, and zooplankton). Most nutrients were converted into plankton, which then became natural food for fish, ensuring complete nutrient utilization. This is beneficial for both water quality improvement and fish reproduction. Therefore, adding a moderate proportion of bagasse to the feed can maximize the effects of water quality improvement, fish reproduction, and even the quality of fish meat.

A two-year plant-based diet alters the fatty acid profile and enzymatic and non-enzymatic lipid metabolites, in the eggs and fry of female rainbow trout

To promote sustainable aquaculture, plant-based ingredients are increasingly being used to replace fish meal (FM) and fish oil (FO) in diets, affecting critical fatty acid (FA) profiles in broodstock diets. These profiles are essential for reproduction and offspring survival. The absence of traditional fish-derived nutrients results in an altered FA composition, particularly a reduction in omega-3 long-chain polyunsaturated fatty acids (LC-PUFAs). This change is detrimental to trout reproduction over the long term. Current research gaps, especially regarding FA profiles and related metabolites, limit our understanding of the reproductive consequences of omega-3 deficient plant-based diets. To fill this knowledge gap, a two-year trial was conducted to compare the reproductive effects (spawning performances, egg quality, embryo development) of two diets on rainbow trout females: a plant-based diet containing linseed (10.8 %), palm (5 %), and sunflower oils (2.7 %), and a commercial diet with high FM (27 %) and FO (12.1 %) content. Both diets were similar in terms of protein (44 %), lipids (23.4 %), and energy (25 kJ/g). The study spanned from initial feeding to first reproduction, and fatty acid profiles and metabolites (selected enzymatic and non enzyamatic metabolites from FA) were examined in the broodstock diet, female muscle tissue, eggs, and fry. Trout fed a plant-based diet showed reduced reproductive traits such as lower weight and fecundity, but egg and embryo quality remained high. Survival and hatching rates were similar to those on commercial diets. The study revealed for the first time the critical role of maternal diet in the generation of lipid metabolites in the offspring, particularly DHA (F4-neuroprostane, maresin, 14-HDoHE) and AA (F2-isoprostane, prostaglandin E and F2, 8–12- 15-HETEs) oxylipins, highlightingthe complex dietary influences on fish reproduction. This work underlines that a plant-based diet significantly affects the the reproductive performance of broodstock trout by altering fatty acid profiles and metabolite levels and highlights the delicate balance between dietary components, oxylipins, and reproductive functions in fish, suggesting the need for more comprehensive studies of their interrelated effects.

Environmental Factors Associated With Fish Reproduction in Regulated Rivers

ABSTRACTHumans have extensively altered rivers to accommodate anthropogenic uses. Dams modify river flow and temperature regimes important for lotic fish reproduction. Yet, assessments of fish production in relation to environmental conditions in regulated rivers are lacking but are needed to guide experimental environmental flows. We evaluated the effects of water temperature and discharge on larval Catostomidae, Sciaenidae, and Clupeidae production to inform environmental flow management. We sampled ichthyoplankton from April through June on the Des Moines and Iowa rivers prior to (2014–2015) and after (2021–2022) an experimental environmental flow was incorporated on the Des Moines River. We used a hurdle model to assess the effects of water temperature, discharge, and discharge variation on larval presence (logistic regression) and density (linear regression). Larval Catostomidae were captured once water temperatures exceeded 15°C, Sciaenidae appeared when water temperature surpassed 18°C, while Clupeidae appeared when water temperature exceeded 20°C. The probability of larval Sciaenidae and Clupeidae presence increased with discharge variation while densities were both positively associated with discharge and discharge variation. The probability of Sciaenidae and Catostomidae larval presence increased with water temperature. Interactions between water temperature and discharge influenced Clupeidae presence and Catostomidae density. The probability of Clupeidae presence increased with discharge at warmer water temperatures. Catostomidae densities increased with discharge at cool water temperature (13°C) and decreased with discharge at warm (25°C) temperatures. Our results provide information about the effects of discharge, discharge variation, and water temperature driving larval fish production in anthropogenically altered rivers to guide environmental flow management.

Growth Performance of Kappaphycus alvarezii and Kappaphycus striatus cultivated in Ekas Bay, East Lombok Regency, West Nusa Tenggara Province

alvarezii is a superior product of Indonesian fisheries, producing carrageenan which is used as a food, cosmetic, and medicinal ingredient. K. striatus is a carrageenan-producing red alga that began to be cultivated in the Ekas waters of East Lombok in 2023. K. striatus is more resistant to epiphytes and sudden climate change. The purpose of this study was to analyze the growth of Kappaphycus alvarezii and Kappaphycus striatus. The research was conducted in Ekas Bay, Jerowaru District, East Lombok Regency. The research was conducted from November 8, 2023, to January 8, 2024. This research used an experimental method with T-test analysis. Treatments in this research are the cultivation of K. alvarezii and K. striatus. Cultivation was carried out at Ekas Bay. Analysis of seaweed carrageenan was carried out in the Laboratory of Fish Production and Reproduction, Aquaculture Study Program, Faculty of Agriculture, Mataram University. The result of this research is K. striatus has a higher absolute weight of 154 g compared to K. alvarezii seaweed which is 72 g. The specific growth rate K. striatus higher at 2,98 % / day compared to K. alvarezii is 1, 98 % / day. The yield of carrageenan of K. alvarezii is 1,95% and K. striatus 0,88%. Antioxidant of K. alvarezii is 5,46 % and K. striatus is 7,42%. Chlorophyll K. alvarezii is 5,77 mg/l and K. striatus is 3,51 mg/l. The conclusion of this study is the growth of K. striatus is faster than K. alvarezii.

Female-biased sex ratios and delayed puberty in two fish species with different Ecologies in an Anthropogenically affected urban lake

In aquatic ecosystems, endocrine-disrupting compounds (EDCs) pose a growing concern for their potential adverse effects on fish reproduction and development. In lake Pyhäjärvi, located in the urban boreal region of Tampere, Finland, a significant number of sexually immature pikeperch (Sander lucioperca) individuals have been identified in size and age categories that are expected to be sexually mature. To explore if this phenomenon is attributed to estrogenic endocrine disruption, we conducted a comprehensive study comparing fish from lake Pyhäjärvi with those from a nearby reference lake, lake Näsijärvi. Roach (Rutilus rutilus), known for its susceptibility to EDCs, was also included for comparison. We examined various parameters in both pikeperch and roach, including size, condition factor, age, reproductive indicators, biometric indices and gonadal histology. We also assessed liver vitellogenin mRNA levels and genetic sex in roach, and measured estrogen levels in lake waters and wastewater treatment plant effluents. Results revealed that approximately one-third of fish in both species exhibited sexual immaturity in lake Pyhäjärvi, with a female-biased sex ratio. Surprisingly, we found no signs of estrogenic endocrine disruption, indicated by the absence of intersex fish in both species. Furthermore, vitellogenin levels in roach closely resembled those in the reference lake. Estrogens were undetectable in the lake waters, suggesting that factors other than estrogenic EDCs, including other potential endocrine disruptors such as PCBs or heavy metals, may be influencing delayed sexual maturity and skewed sex ratios. Further inquiry is needed to pinpoint these underlying causes. Our study provides essential baseline information on fish sexual development in lake Pyhäjärvi, emphasizing the need for ongoing monitoring and research to understand delayed sexual maturity and biased sex ratios. This is vital given the increasing concern about EDC impacts on aquatic ecosystems and the necessity for effective management strategies to protect these ecosystems' health and integrity.

Reproductive morphophysiology of an iteroparous batch spawner fish: from early follicle development to ovulation.

Batch spawner fishes develop successive clutches of oocytes which allows them to participate in many reproductive cycles during their adult life (iteroparous) and spawn in multiple events within each breeding cycle. Here, ovarian follicular development was morpho-functionally analyzed in females of the iteroparous batch spawner fish Gymnocorymbus ternetzi. To obtain better insights into the reproductive morpho-physiology in batch spawners, the objective of this research was to analyze the dynamics of the follicular development, with its hormonal regulation between two active reproduction events. We found that over 16 days, follicles progressed asynchronously to chromatin nucleolus, Primary and Secondary growth stages of oogenesis with progressive secretion of 17β-estradiol (E2). During the end of secondary growth, the increase in 17α,20β-dihydroxy-4-pregnen-3-one (17,20β-p) was measured relative to the maturation process of the ovarian follicles (e.g., nuclear migration and its rupture during the resumption of meiosis). Interestingly, an additional increase in E2 was observed after fish reproduction, probably related to the recruitment of new batch follicles for secondary growth. We also measured the high values of multiple condition factor post-reproduction measurements, reflecting more energy invested during the pre-reproductive process. We also quantified high concentrations of 17,20β-p, probably related to the recruitment of a new batch of oogonia to meiosis, presumably secreted by post-ovulatory follicles, after fish reproduction. We finally found that fish without exposure to reproductive stimulus developed a regression phase at day 24, characterized by massive follicle atresia, that allow them to recycle energy and constitutive materials of the follicles invested during oogenesis for another reproductive cycle.

Investigating fish reproduction phenology and essential habitats by identifying the main spatio-temporal patterns of fish distribution

Abstract Fish spawning phenology is a major concern for conservation and fisheries management. New intensive data sources, such as GPS-based tracking data and high-resolution catch declaration data, are becoming increasingly available in the field of marine ecology. These data benefit from high spatiotemporal resolution and open new research avenues for investigating the interannual variability in fish phenology. In this paper, we demonstrate how an integrated species distribution model informed by commercial catch data combined with spatiotemporal dimension reduction methods known as empirical orthogonal functions (EOFs) can be used to synthesize spatiotemporal signals in fish reproduction phenology. Specifically, we address the following questions: (1) Can we identify seasonal spatial patterns that can be interpreted in terms of reproductive phenology and essential habitats? (2) Can we identify changes in reproductive phenology over time? (3) Are these changes related to environmental drivers? The analysis illustrates the reproductive phenology of three key commercial species in the Bay of Biscay (sole, hake, and sea bass). The EOF analysis emphasized strong seasonal spatiotemporal patterns that correspond to reproduction patterns and feeding patterns. Based on this methodology, we identified seasonal variations in the timing of reproduction, and we related these variations to sea surface temperature, a key driver of fish reproduction.

Study on the key ecological factors for the reproduction of Gymnocypris eckloni in the upper reaches of the Yellow River.

The development of hydroelectric projects has adversely affected the reproductive activities of downstream fish species. To facilitate the natural reproduction of fish and restore spawning grounds post-dam construction, it is imperative to explore the ecological factors crucial for their reproduction. Currently, various research methods with different advantages and limitations are employed for this purpose. Using identified spawning locations and periods as clues, we quantitatively investigate the flow velocity, water depth, water temperature, and riverbed substrate required for spawning. The results are validated using habitat simulation methods, aiming to establish a more scientific approach to explore ecological factors affecting fish reproduction. This study provides a more scientific, systematic, and detailed report on the ecological factors required for the spawning of Gymnocypris eckloni: flow velocity ranging from 0.19 to 0.97 m/s, water depth from 0.28 to 1.12 m, water temperature between 11.4 and 15.2°C, and predominantly gravel substrate. The reliability of the results was verified in another spawning ground, with good verification results. This research provides crucial data for the bio-mimetic reproductive technology of Gymnocypris eckloni and the restoration of spawning grounds for natural fish reproduction post-dam construction. It addresses the lack of suitable ecological factor data for protective fish species in the upper reaches of the Yellow River. The method exhibits strong scientific, accurate, and implementable characteristics.

Elevated temperature impairs gonadal development by suppressing the expression of the genes for kisspeptin, GnRH1 and GTH subunits in Nile tilapia Oreochromis niloticus

Temperature is a preeminent factor in the regulation of fish reproduction and hinders gonadal development beyond a specific threshold. To comprehend the molecular mechanism responsible for reproductive suppression at different temperature, expression of the genes encoding kisspeptin (kiss2), gonadotropin-releasing hormone (gnrh1) and their receptors (gpr54, gnrh1r) in the brain, and the gonadotropin (GTH) subunits (fshb and lhb) in the pituitary were studied in juvenile Nile tilapia (Oreochromis niloticus) along with gonadal histology. Fish were acclimatized to three distinct temperatures, including 31 °C, 34 °C and 37 °C for 14 days. The mRNA levels of kiss2, gpr54, gnrh1, and gnrh1r were significantly decreased at 37 °C compared to 31 °C and 34 °C in the both sexes. In parallel, the expression level of fshb in the both sexes and lhb in the female were significantly lower at 37 °C in the pituitary. Histologically, the gonads of both sexes had normal growth of gametes at control temperature (31 °C), whereas the spermatogenesis and oocyte maturation were slowed down and atretic oocytes were found in the ovary at 37 °C acclimation temperature. Taken together, the results imply that elevated temperature beyond the specific threshold may have a negative impact on reproduction by suppressing the gene expressions of kisspeptin/GnRH1/GTH system and eventually restrains normal growth and maturation of gametes in the both sexes of Nile tilapia.

Insecticides Cypermethrin and Chlorpyrifos Exposure: Effects on Sperm Motility and Fertility in Cyprinus carpio (Cypriniformes, Cyprinidae)

The agricultural production of the Argentine Pampa is based on intensive cultures, and the most widely used insecticides correspond to cypermethrin (pyrethroid) and chlorpyrifos (organophosphate), among others. Sperm motility and fertility assessments are essential topics for biology and population dynamics studies on fish species. In this study the alterations of these endpoints after exposure to commercial formulation of both insecticides were used to analyze the effects on common carp sperm. After the in vitro exposure at nominal concentrations of 0.25, 0.5, 1, and 2 μg/L of cypermethrin, a significant reduction in motility in 0.5 μg/L concentrations was observed respect control group. The same nominal concentrations were tested for chlorpyrifos, and the same significative effect was detected at 2.0 μg/L. Fertilization rate was significantly reduced at concentrations from 0.5 μg/L cypermethrin exposure, and from 1.0 μg/L in the case of chlorpyrifos. Eggs LC50 / 24 h (95% confidence limit) exposed to cypermethrin was 0.57 μg/L (0.36 - 0.88), and exposed to chlorpyrifos was 2.45 μg/L (1.13-5.29). However, is still debatable how these insecticides impact on fish reproduction, using this in vitro scenario we found a clear reduction in sperm motility and fertility.