Fish Poecilia Reticulata Research Articles

Histopathologic changes in different organs during mycobacteriosis in guppy (Poecilia reticulata) and japanese medaka (Oryzias latipes)

Total histological sections of laboratory fish Poecilia reticulata and Oryzias latipes with pronounced multiple organ failure caused by Mycobacterium infection (Mycobacterium sp.) were analyzed. The pathogenesis of the disease in question is expressed in the occurrence, in various tissues, of foci of inflammation, subsequently forming a connective tissue capsule — granuloma. These lesions were observed in almost all organs of the abdominal cavity of the fish. The largest and most common lesions were found in the pancreas, kidneys and liver (from 478.6 microns to 858.4 microns), significantly disrupting organ functions, which is a clinical picture characteristic of mycobacteriosis. The occurrence of granulomas and their average sizes in organs such as the intestine and gills were significantly lower and amounted to 328.3 and 468.9 microns, respectively. Data on the stages of granuloma development in different organs of fish are presented. The initial stage of granuloma development consists of clusters of macrophage-like cells, lymphocytes, granulocytes and a small number of cellular residues. At the final stage of development, it is a focus, including an eosinophilic-stained caseous-necrotic nucleus and a shell consisting of epithelioid macrophages. It is shown that there is a relationship between the size parameters of granulomas, the frequency of their occurrence and the degree of organ damage. The localization of granulomas and the degree of their development in guppies and medaka were similar, indicating the absence of species-specific virulence. It follows from this that any warm-water fish species cultivated under controlled conditions are at risk. This requires monitoring for signs of disease and regular preventive measures.

Invasive New and Old World freshwater species in isolated springs of the Atacama Desert: implications for native species

ABSTRACT Invasive species can significantly alter invaded ecosystems. In this study, we report the presence of two invasive species, the poeciliid fish Poecilia reticulata and the gastropod Melanoides tuberculata, in three isolated springs from the coast of the Atacama Desert in Antofagasta city, northern Chile. Both species were identified through diagnostic morphological features and phylogenetic analysis. This is the first confirmed record of P. reticulata in natural ecosystems of Chile. The finding of M. tuberculata represents the first record of the species in the Antofagasta Region, and the third in the country. Considering the well-documented adverse effects of both species on invaded ecosystems and their high potential for spread, we recommend the prompt implementation of mitigation measures. These should focus on the direct mechanical removal of these species, given the relatively straightforward sampling process and the relatively small size of the springs. Such measures would significantly contribute to the preservation of native species, particularly those categorized as vulnerable.

Effects of the invasive fish Poecilia reticulata on the behavioral response of Daphnia pulex to the exotic submerged macrophyte Egeria densa

AbstractThe high-elevation plateaus of the inter-Andean valleys are home to shallow lakes that have become eutrophic. These lakes share similarities with shallow lakes in temperate and subtropical areas. Because native species diversity is low, invasive species dominate the fish and macrophytes communities. The study aimed to investigate the behavioral response of the local Daphnia pulex from the Andean shallow Lake Yahuarcocha to the exotic submerged macrophyte Egeria densa and the exotic fish Poecilia reticulata. Laboratory habitat choice experiments revealed that D. pulex from Lake Yahuarcocha strongly avoid E. densa, irrespective of the presence of the fish P. reticulata or chemical cues indicating fish predation on D. pulex. This observation could be explained by the fact that P. reticulata displayed a strong attraction to E. densa during the daytime, probably to avoid bird predation. D. pulex from the nearby Lake San Pablo where P. reticulata is absent but where the fish community is dominated by Oncorhynchus mykiss displayed the same avoidance behavior to submerged macrophytes as D. pulex from Lake Yahuarcocha. These results indicate that macrophytes in these high-elevation shallow lakes may not facilitate top-down control of phytoplankton, since plants do not offer refuge to D. pulex from fish predation.

The effect of mercury ions on the metabolic activity of Poecilia Reticulata cells

Among anthropogenic factors polluting ecosystems and affecting living organisms, mercury, and its compounds are the most toxic. In this study, we investigated the effect of mercury ions on freshwater live-bearing fish Poecilia reticulata. The cytotoxicity of mercury was analyzed on Poecilia reticulata fry using the MTT test. Studies have shown that small concentrations of mercury can have a stimulating effect on the metabolic activity of fish cells, but at high concentrations, the mercury had a depressing effect.

Are fire suppressants “nontoxic”? Acute toxicity, DNA damage and lipid peroxidation in fish (Poecilia reticulata) exposed to low concentrations

During an emergency in the Port of Santos (Brazil), large volumes of Aqueous film forming foams (AFFFs) were used, producing an effluent containing a mixture of AFFFs, gasoline and ethanol, which reached the Santos Estuarine System and caused massive fish deaths. This investigation aimed to study the toxicity of three AFFFs (Agefoam; Cold Fire; and F500 Fire) used in the fire fighting on the fish Poecilia reticulata. Acute toxicity tests were conducted using adult individuals, and the lethal concentration to 50% organisms (LC50) was calculated after 96 h, together with the low observed (LOEC) and the no observed effect concentrations (NOEC). Gills and liver from the exposed fish were analyzed for DNA damage and membranes’ lipoperoxidation (LPO). All the AFFFs caused significant fish mortalities, and the LOECs were 0.01% for Agefoam® and 0.001% for F500® and Cold Fire®. Toxicity thresholds were determined for F500® (LC50–48 h = 0.01%), Agefoam® (LC50–96 h = 0.008621%) and the Cold Fire® (LC50–96 h = 0.001221%). Fish exposed to 0.01% and 0.001% of Agefoam® and Cold Fire® did not showed significant effects on DNA damage, while those exposed to F500® presented significantly reduced damages at 0.00001%. The exposed fish presented reduced levels of LPO in most concentrations, excepting those exposed to Cold Fire® (gills) and Agefoam® (liver). The results suggest that the fish deaths were likely caused by direct action of the tensoactives and not by the oxidation induced by reactive oxygen species.

Potential Submerged Macrophytes to Mitigate Eutrophication in a High-Elevation Tropical Shallow Lake—A Mesocosm Experiment in the Andes

Submerged macrophytes promote water clarity in shallow lakes in temperate regions via zooplankton refuge, allelopathy, and nutrient competition with phytoplankton, thereby increasing zooplankton grazing. However, in high-altitude Andean ecosystems, these interactions in shallow lakes have received far less attention. To understand the role of submerged plants in a relatively cold ecosystem (typical for the Andean region), two 100 L experiments were conducted in Yahuarcocha Lake, which has a permanent cyanobacterial bloom. In our first experiment, we evaluated the response of the cyanobacteria bloom to different concentrations of Egeria densa (15%, 35%, and 45% PVI). In the second experiment, we investigated the interactions between E. densa (35% PVI), zooplankton, and the small-sized fish Poecilia reticulata as well as their impacts on phytoplankton. We found a strong reduction in cyanobacteria in the presence of E. densa, whereas P. reticulata promoted cyanobacteria dominance and zooplankton had a null effect on phytoplankton. Remarkably, the combination of E. densa, fish, and zooplankton substantially reduced the algae. Our findings showed that the cyanobacteria bloom decreased in the presence of E. densa, thereby increasing the water clarity in the high-elevation eutrophic ecosystem in the Andes. This effect depended on the plant volume inhabited and the small-sized fish biomass.

Avoidance Response: A More Important Determinant of Population Immediate Decline in Guppy Fish (Poecilia reticulata Peters, 1859) Exposed to Pesticides

This study investigated the ability of Paraquat (herbicide) and Dichlorvos (insecticide) to elicit avoidance response in the population of Guppy fish, Poecilia reticulata and predict the population immediate decline (PID) of P. reticulata when exposed to both agrochemicals. A 96-h forced system (FS) bioassay was each conducted in five duplicate systems, each with a control experiment. The avoidance response was examined using a non-forced multi-compartmented static system (NFS). The guppies (n = 3 guppies per concentration of 6 compartments in quadruplet) were exposed to a gradient of Paraquat (0, 2.5, 5.0, 7.5, 10.0 and 15.0 mgL-1) and Dichlorvos (0, 1.6, 2.6, 3.0, 3.2 and 4.0 mgL-1). Their distributions were examined at 20 min intervals for a 3-h period (n=9observation periods). The results from 96-h FS were dose-dependent with the highest percentage mortality being 85.7% for Paraquat and 78.6% for Dichlorvos in their respective highest concentrations. The 3-h NFS exposure showed statistically significant concentration-dependent spatial avoidance. The P. reticulata avoided the lowest concentration of Paraquat (2.5mgL-1) and Dichlorvos (1.6 mgL-1) by 68.3% and 48.3% respectively. The avoidance increased significantly (p < 0.005) to 75%, for the highest concentrations of both test chemicals (15.0 and 4.0 mgL-1). The 3-hr AC50 value revealed that the guppies were more sensitive to Paraquat (0.37 mgL-1) than Dichlorvos (1.73 mgL-1). The PID was driven by the avoidance behavior (NFS) of the guppies rather than mortality (FS). The FS heretofore overestimate the environmental risk of contamination due to mandatory exposure of mobile organisms to contaminants. Rather than the traditional FS systems, NFS should be adopted and incorporated into typical bioassays for better predictive results.

Навчальні експерименти з використанням живих організмів: біоетичні обґрунтування корекції методик

The relevance of the topic of the article is due to two trends in the world and in Ukraine: the spread of research practices that need to be understood in the discourse of bioethics, and attempts to introduce bioethics (or its basic ideas and principles) in the educational process of technical universities. These two trends are combined in the practice of using animals in scientific experiments. Taking into account the fact that a component of such research in not only scientific, but also educational experiments, this topic becomes an urgent problem in the discourse of the philosophy of education. The purpose of the article is to present and analyze the experience of correcting the methods of educational and demonstration experiments using living organisms, which are carried out at the Odessa Polytechnic State University. As examples, the course of laboratory work on the study of the influence of wastewater from foundry dumps on living organisms (specialty 136-Metallurgy) and an experiment to study the effect of photon irradiation on biological objects in the aquatic environment (specialty 163-Biomedical engineering) are described. Guppy fish (Poecilia reticulata Peters) are used in both experiments. The results of the analysis of the correction of the methods of these experiments form the scientific novelty in three aspects: 1) the substantiation of the need for the formation of bioethical competencies is given not only for physicians and veterinarians, but also for engineers of various specialties; 2) an additional principle of bioethics of experiments on animals is proposed and tested - the principle of early stopping of an experiment (educational and demonstration) at a certain stage; 3) it is shown that giving students the opportunity to make decisions about changing the experiment procedure allows them to better understand the boundaries of what is necessary and sufficient, forms their willingness to take responsibility for the result of the experiment and for the lives of people and animals.

Immunolocalization of Vasa, PIWI, and TDRKH proteins in male germ cells during spermatogenesis of the teleost fish Poecilia reticulata

Vasa, PIWI and TDRKH are conserved components of germ granules that in metazoans are involved in germline specification and differentiation, as documented by mutational experiments in some model animals. So far, investigations on PIWI during spermatogenesis of fish has been limited to a few species, and no information is available for TDRKH, another protein involved in the piRNA pathway. In this study, the immunolocalization of these three germline determinants was analyzed in male gonads of the teleost fish Poecilia reticulata to document their localization pattern in the different stages of germ cell differentiation.To analyze their distribution pattern during the different stages of spermatogenesis we performed immunohistochemistry (IHC) and immunofluorescence (IF) assays using primary polyclonal antibodies after testing their specificity with Western Blot. Moreover, sections of testis stained with haematoxylin and eosin clarified the structural organization of P. reticulata testis, while the use of the confocal microscope and the nuclear staining clarified the different stages of germ cell differentiation during spermatogenesis.The results showed that Vasa, PIWI and TDRKH were specifically immunolocalized in the germ cells of P. reticulata, with no specific signal detected in Sertoli cells and in other somatic cells of the gonad. These markers were detected in all stages of differentiation from early spermatogonia to advanced spermatids. Vasa staining was the strongest in spermatogonia, and then decreases throughout differentiation. Instead, both PIWI and TDRKH staining increases during differentiation, and their distribution pattern, similar to what observed in the mouse, suggests their concerted participation in the piRNA pathway also in this fish.

Histomorohological Studies on Ovary of Guppy (Poecilia Reticulata) And Development of Follicular Placenta

The larvivorous fish Poecilia reticulata was propagated prolifically in the garden for control of mosquito vectors and later redistributed in a number of water reservoirs, in different villages nearby Dapoli. The gravid live bearing females were quickly dissected for their ovaries and embryos. The developed embryo with yellow rounded yolk sac, the remnants of the follicular placental tissue and thick vascular network of connective tissue was also observed.

Acute and Chronic Toxicity of Endocrine Disruptive Heavy Metals and Pesticides Exposed to Freshwater Fish P. reticulata and P. sphenops

Environmental monitoring is a recent world-wide approach to save the future in line. The present study focuses on toxicity of heavy metals and pesticides on the freshwater aquarium fish (Poecilia reticulata and Poecilia sphenops). The study intense on drawing the acute and chronic safe levels of metals and pesticide exposed to 96 h and 28 day respectively. On exposure, the fish were observed to be under stress and showed excitability. It was observed that both species were highly sensitive to arsenic and cypermethrin, meanwhile resistant to cadmium and chlorpyrifos. The acute safe levels for As irrespective of species was comparatively lesser than that of Cd exposed fish and the range of safe values for pesticides exposure were between 0.018 and 0.059 ppb. As the water quality is influencedby many environmental factors, the present study helps the aquarist in monitoring the safe level of toxicants in the medium. This in turn increases the economic growth of the aquarist.

First record of the non-native fish Poecilia reticulata (Cyprinodontiformes: Poeciliidae), in Chiapas, southern Mexico

Introduction: Due to its colors, shape, size, and simplicity of care, the neotropical fish Poecilia reticulata (guppy) is popular in the aquarium trade. It is also valued as mosquito control and is now found in most of the world. Objective: To report its presence in southern Mexico. Methods: Fish were captured with seine nets in a tributary of the Grijalva River, Chiapas, in August 2019, and March 2020. Results: Two hundred and fifty individuals of P. reticulata were captured. Conclusion: The species, found in México in 1971, has extended its range to the Grijalva Usumacinta river system.

Environmentally relevant concentrations of benzophenone-3 induce differential histopathological responses in gills and liver of freshwater fish.

BP-3 is one of the most used organic UV filters. However, its widespread use and release into aquatic environment can induce ecotoxicological impact on aquatic organisms. Thus, the aim of the current study is to evaluate the gills and liver of freshwater fish Poecilia reticulata subjected to acute exposure (96 h) to BP-3 at environmentally relevant concentrations (10-1000 ng L-1). The study was based on adopting qualitative and semi-quantitative approach to assess histopathological changes and integrated the biomarker response in order to investigate organ-specific responses to BP-3 exposure. BP-3 has induced high histopathological index associated with circulatory disturbances, as well as with regressive and immunological changes in gills, whereas the hepatic histopathological index was associated with circulatory disturbances. Moreover, lower BP-3 concentrations were mostly associated with changes in gills, whereas higher BP-3 concentration was mostly linked to hepatic changes. In conclusion, acute exposure to BP-3 at environmentally relevant concentrations had stronger impact on gills than on the liver of P. reticulata, which confirmed organ-specific responses to UV filters.

Co-exposure of iron oxide nanoparticles and glyphosate-based herbicide induces DNA damage and mutagenic effects in the guppy (Poecilia reticulata)

Iron oxide nanoparticles (IONPs) have been tested to remediate aquatic environments polluted by chemicals, such as pesticides. However, their interactive effects on aquatic organisms remain unknown. This study aimed to investigate the genotoxicity and mutagenicity of co-exposure of IONPs (γ-Fe2O3 NPs) and glyphosate-based herbicide (GBH) in the fish Poecilia reticulata. Thus, fish were exposed to citrate-functionalized γ-Fe2O3 NPs (0.3 mg L−1; 5.44 nm) alone or co-exposed to γ-Fe2O3 NPs (0.3 mg L−1) and GBH (65 and 130 μg of glyphosate L−1) during 14 and 21 days. The genotoxicity (DNA damage) was analyzed by comet assay, while the mutagenicity evaluated by micronucleus test (MN test) and erythrocyte nuclear abnormalities (ENA) frequency. The co-exposure induced clastogenic (DNA damage) and aneugenic (nuclear alterations) effects on guppies in a time-dependent pattern. Fish co-exposed to NPs and GBH (130 μg glyphosate L−1) showed high DNA damage when compared to NPs alone and control group, indicating synergic effects after 21 days of exposure. However, mutagenic effects (ENA) were observed in the exposure groups after 14 and 21 days. Results showed the potential genotoxic and mutagenic effects of maghemite NPs and GBH co-exposure to freshwater fish. The transformation and interaction of iron oxide nanoparticles with other pollutants, as herbicides, in the aquatic systems are critical factors in the environmental risk assessment of metal-based NPs.

Death of guppy fish (Poecilia reticulata) leukocytes induced by in vivo exposure to temephos and spinosad

ABSTRACT Temephos and spinosad are pesticides used for control of vector-borne diseases such as dengue, chikungunya and zika. However, the inadequate use of these substances has affected the health of non-target organisms. The aim of this study was to evaluate and compare, the effects of temephos and spinosad on leukocyte viability and death, using guppy fish (Poecilia reticulate) as a model organism. Guppies were exposed to temephos (10 mg/L) and spinosad (0.5 mg/L) for 7, 14, and 21 days. Afterwards, they were placed in pesticide-free fish tanks (7, 35, and 70 days) for recovery. The results showed that exposure to temephos caused leukocyte death, even at 35 days of recovery. Contrarily, the exposure to spinosad did not cause leukocyte death. This research show, for the first time, that a single dose of temephos causes apoptosis up to 56 days post-exposition, indicating that this pesticide induces chronic effects on immune response cells.

Altered phagocytic capacity due to acute exposure and long-term post-exposure to pesticides used for vector-borne disease as dengue

ABSTRACT Spinosad and temefos are widely used pesticides for chemical control of dengue vector-borne disease (Aedes aegypti). The aim of this study was to compare the effect of acute exposure (7 days) to spinosad (0.5 mg A.I. L−1) and temefos (10 mg A.I. L−1), concentrations used by the Mexican Ministry of Health, on phagocytic capacity (PC) of mononuclear cells of guppies fish (Poecilia reticulata), as well as to assess PC in fish, at 96 days after exposure to those pesticides. Obtained results indicated that spinosad did not alter PC, while an acute exposure to temefos significantly affected phagocytosis and this parameter was maintained downed even 96 days after the acute exposure, suggesting that the immunotoxic effects of temefos may be chronic.

ИСПОЛЬЗОВАНИЕ СОРБЕНТОВ В РЫБОВОДСТВЕ

The use of sorbents at present is a promis-ing method for improving fish growing con-ditions. One of the types of sorbents is ver-miculite, a natural mineral that has highly effective sorbing properties. It has been established that it is active against heavy metal ions, organic compounds such as phe-nol, dioxin, oil products, carcinogens, toxic chemicals, nitrites and nitrates, chlorine and fluorine compounds. The aim of the study is to study the effect of sorbent-vermiculite on the amount of ni-trites and nitrates in water. When setting the goal, the following tasks were developed: to study the hydrochemical parameters and evaluate the effect of vermiculite on the vital activity / vitality of laboratory fish. The object of the study was a laboratory guppy fish (Poecilia reticulata). The fish was kept in aquariums with a volume of 10 liters. at room temperature with a natural change in day and night. They fed the fish with food "Waka TropiFlek for all types of fish." Ver-miculite with a particle size of 1-5 mm was used as a sorbing substance. The study con-sisted of a control and one experimental group, 6 fish were in each aquarium. Ver-miculite was added to the experimental group, pre-packaged / wrapped in gauze and subsequently dipped in water. The duration of the experiment was 30 days. Studies have shown that the sorbent reduces the amount of nitrates and nitrites, reduces the rate of their accumulation in water and supports the vital activity of fish at critical values of the above hydrochemical parame-ters. According to the document “Strategy for the Development of Aquaculture in the Russian Federation for the Period Until 2020” (approved by the Ministry of Agricul-ture of the Russian Federation on September 10, 2007), in the Russian Federation it is necessary to determine the way to achieve a qualitative new state of aquaculture. Vermic-ulite may be an actual tool for use in the cultivation / reproduction of aquatic organ-isms

Potential of fascaplysin and palauolide from Fascaplysinopsis cf reticulata to reduce the risk of bacterial infection in fish farming

Marine natural products isolated from the sponge Fascaplysinopsis cf reticulata, in French Polynesia, were investigated as an alternative to antibiotics to control pathogens in aquaculture. The overuse of antibiotics in aquaculture is largely considered to be an environmental pollution, because it supports the transfer of antibiotic resistance genes within the aquatic environment. One environmentally friendly alternative to antibiotics is the use of quorum sensing inhibitors (QSIs). Quorum sensing (QS) is a regulatory mechanism in bacteria which control virulence factors through the secretion of autoinducers (AIs), such as acyl-homoserine lactone (AHL) in gram-negative bacteria. Vibrio harveyi QS is controlled through three parallel pathways: HAI-1, AI-2, and CAI-1. Bioassay-guided purification of F. cf reticulata extract was conducted on two bacterial species, i.e., Tenacibaculum maritimum and V. harveyi for antibiotic and QS inhibition bioactivities. Toxicity bioassay of fractions was also evaluated on the freshwater fish Poecilia reticulata and the marine fish Acanthurus triostegus. Cyclohexanic and dichloromethane fractions of F. cf reticulata exhibited QS inhibition on V. harveyi and antibiotic bioactivities on V. harveyi and T. maritimum, respectively. Palauolide (1) and fascaplysin (2) were purified as major molecules from the cyclohexanic and dichloromethane fractions, respectively. Palauolide inhibited QS of V. harveyi through HAI-1 QS pathway at 50 μg ml–1 (26 μM), while fascaplysin affected the bacterial growth of V. harveyi (50 μg ml–1) and T. maritimum (0.25 μg). The toxicity of fascaplysin-enriched fraction (FEF) was evaluated and exhibited a toxic effect against fish at 50 μg ml–1. This study demonstrated for the first time the QSI potential of palauolide (1). Future research may assess the toxicity of both the cyclohexanic fraction of the sponge and palauolide (1) on fish, to confirm their potential as alternative to antibiotics in fish farming.

Anthropogenic Factors Driving Recent Range Expansion of the Malaria Vector Anopheles stephensi.

The malaria vector Anopheles stephensi is found in wide tracts of Asia and the Middle East. The discovery of its presence for the first time in the island of Sri Lanka in 2017, poses a threat of malaria resurgence in a country which had eliminated the disease in 2013. Morphological and genetic characterization showed that the efficient Indian urban vector form An. stephensi sensu stricto or type form, has recently expanded its range to Jaffna and Mannar in northern Sri Lanka that are in proximity to Tamil Nadu state in South India. Comparison of the DNA sequences of the cytochrome oxidase subunit 1 gene in An. stephensi in Jaffna and Mannar in Sri Lanka and Tamil Nadu and Puducherry states in South India showed that a haplotype that is due to a sequence change from valine to methionine in the cytochrome oxidase subunit 1 present in the Jaffna and Mannar populations has not been documented so far in Tamil Nadu/Puducherry populations. The Jaffna An. stephensi were closer to Tamil Nadu/Puducherry populations and differed significantly from the Mannar populations. The genetic findings cannot differentiate between separate arrivals of the Jaffna and Mannar An. stephensi from Tamil Nadu or a single arrival and dispersion to the two locations accompanied by micro-evolutionary changes. Anopheles stephensi was observed to undergo preimaginal development in fresh and brackish water domestic wells and over ground cement water storage tanks in the coastal urban environment of Jaffna and Mannar. Anopheles stephensi in Jaffna was resistant to the common insecticides deltamethrin, dichlorodiphenyltrichloroethane and Malathion. Its preimaginal development in wells and water tanks was susceptible to predation by the larvivorous guppy fish Poecilia reticulata. The arrival, establishment, and spread of An. stephensi in northern Sri Lanka are analyzed in relation to anthropogenic factors that favor its range expansion. The implications of the findings for global public health challenges posed by malaria and other mosquito-borne diseases are discussed.

A comparison of the larvivorous habits of exotic Poecilia reticulata and native Aplocheilus parvus

BackgroundThe exotic fish Poecilia reticulata is promoted in the tropics as a biological control agent for aquatic pathogenic carriers, such as mosquitoes. Such control measures are often adopted blindly, ignoring the potential of native species and the adverse effects of introduced species. The present study was conducted to assess the diet composition of two species of fish, the native Aplocheilus parvus and exotic P. reticulata, and to assess the availability of food items in their natural environment in four types of aquatic systems. Diet composition was estimated using 24 h gut contents analysis, in a clay quarry pit and a perennial reservoir for A. parvus, and in a man-made canal and a second-order natural stream for P. reticulata. Food items in these environments were quantified by analyzing water samples collected every 2 h.ResultsThe diet of A. parvus in the clay quarry pit and reservoir consisted of adult or larval stages of Insecta, Maxillopoda and Malacostraca. In both habitats, A. parvus selectively fed on insect parts and insect larvae. The diet of P. reticulata consisted of filamentous algae, diatoms and detritus. The diet of A. parvus showed active selection of insectivore food items against their low availability. In contrast, the diet of P. reticulata showed consumption of food items in accordance with their availability in the environment. The highest mean number of food items in the gut for A. parvus was recorded around mid-day in the clay quarry pit, but no peak feeding time was identified in the perennial reservoir. For P. reticulata, peak feeding was recorded around mid-day in both the habitats.ConclusionIrrespective of the type of environment and rate of occurrence, A. parvus preferred insect and insect larvae, whereas P. reticulata consumed the most readily available food items. The active selection of insects by A. parvus suggests they may have value as a biological control agent.