Fish Behavior Research Articles

Learning obstacle avoidance and predation in complex reef environments with deep reinforcement learning

The reef ecosystem plays a vital role as a habitat for fish species with limited swimming capabilities, serving not only as a sanctuary and food source but also influencing their behavioral tendencies. Understanding the intricate mechanism through which fish adeptly navigate the moving targets within reef environments within complex water flow, all while evading obstacles and maintaining stable postures, has remained a challenging and prominent subject in the realms of fish behavior, ecology, and biomimetics alike. An integrated simulation framework is used to investigate fish predation problems within intricate environments, combining deep reinforcement learning algorithms (DRL) with high-precision fluid-structure interaction numerical methods-immersed boundary lattice Boltzmann method (lB-LBM). The Soft Actor-Critic (SAC) algorithm is used to improve the intelligent fish's capacity for random exploration, tackling the multi-objective sparse reward challenge inherent in real-world scenarios. Additionally, a reward shaping method tailored to its action purposes has been developed, capable of capturing outcomes and trend characteristics effectively. The convergence and robustness advantages of the method elucidated in this paper are showcased through two case studies: one addressing fish capturing randomly moving targets in hydrostatic flow field, and the other focusing on fish counter-current foraging in reef environments to capture drifting food. A comprehensive analysis was conducted of the influence and significance of various reward types on the decision-making processes of intelligent fish within intricate environments.

Baseline polycyclic aromatic hydrocarbon maternal transfer data in Lesser Numbfish Narcine brasiliensis (Elasmobranchii: Batoidea) from an impacted estuary in Southeastern Brazil

Maternal offloading of polycyclic aromatic hydrocarbons (PAHs) poses a significant exposure route for developing embryos, with implications for subsequent generations. Despite known developmental effects regarding fish physiology and behavior, maternal PAH transfer assessments in elasmobranchii are still lacking. This study investigated PAH contamination and maternal transfer in one female Lesser Numbfish (Narcine brasiliensis) electric ray and seven embryos for the first time. Naphthalene was identified as the predominant low molecular weight PAH, and dibenzo[a,h]anthracene was the most abundant high molecular weight compound. Most embryos exhibited some level of PAH exposure, with varying accumulation patterns potentially influenced by size, developmental stage, and yolk absorption rates. Further investigation is warranted to understand the impacts of PAH maternal offloading on elasmobranchii uterine contents and embryos.

Dining in danger: Resolving adaptive fish behavior increases realism of modeled ecosystem dynamics.

Animals occupying higher trophic levels can have disproportionately large influence on ecosystem structure and functioning, owning to intricate behavioral responses to their environment, but the effects of behavioral adaptations on aquatic ecosystem dynamics are underrepresented, especially in model studies. Here, we explore how adaptive behavior of fish can affect the dynamics of aquatics ecosystems. We frame fish behavior in the context of the central trade-off between feeding and predation, calculating the optimal level of feeding determined by ambient food availability and predation risk. To explore whole-ecosystem consequences of fish behavior, we embed our behavioral model within the Water Ecosystems Tool (WET), a contemporary end-to-end aquatic ecosystem model. The principle of optimality provides a robust and mechanistic framework for representing animal behavior that is relevant for complex models, and can provide a stabilizing effect on model dynamics. The model predicts an emergent functional response similar to Holling type III, but with richer dynamics and a more rigorous theoretical foundation. We show how adaptive fish behavior works to stabilize food web dynamics compared to a control model with no optimal behavior, and how changing the strength of the underlying trade-off has profound effects on trophic control and food web structure. Furthermore, we demonstrate how including fish behavior allows for an overall more realistic response of the model system to environmental perturbation in the form of nutrient enhancement. We discuss the structuring effects of behavioral adaptations in real ecosystems, and how approaches like this one may benefit aquatic ecological modeling. Our study further highlights how a mechanistic approach based on concepts from theoretical ecology can be successfully implemented in complex operational models resulting in improved dynamics and descriptive power.

Hypothalamic integration of nutrient sensing in fish.

The hypothalamus plays a crucial role in regulating feeding behavior in fish. In this Review, we aim to summarise current knowledge on specific mechanisms for sensing glucose, fatty acids and amino acids in fish, and to consider how this information is integrated in the hypothalamus to modulate feed intake. In fish, specific neuronal populations in the nucleus lateralis tuberalis (NLTv) of the hypothalamus are equipped with nutrient sensors and hormone receptors, allowing them to respond to changes in metabolite levels and hormonal signals. These neurons produce orexigenic (Npy and Agrp) and anorexigenic (Pomc and Cart) neuropeptides, which stimulate and suppress appetite, respectively. The modulation of feeding behavior involves adjusting the expression of these neuropeptides based on physiological conditions, ultimately influencing feeding through reciprocal inhibition of anorexigenic and orexigenic neurons and signalling to higher-order neurons. The activation of nutrient sensors in fish leads to an enhanced anorexigenic effect, with downregulation of agrp and npy, and upregulation of cart and pomc. Connections between hypothalamic neurons and other populations in various brain regions contribute to the intricate regulation of feeding behaviour in fish. Understanding how feed intake is regulated in fish through these processes is relevant to understanding fish evolution and is also important in the context of aquaculture.

The water content, apoptosis, and proliferation of the brain in marine medaka affected by seawater acidification.

A possible explanation for ocean acidification-induced changes in fish behavior is a systemic effect on the nervous system. Three biological barriers at the blood-brain interface effectively separate the brain from the body fluids. It is not known whether fish brain regions in contact with these barriers are affected by acidification. Here, we studied structural changes in medaka (Oryzias melastigma) brain regions contacting cerebrospinal fluid (CSF) after short-term (7 days) CO2 exposure. The brain water content decreased significantly and the superficial structure of the pia mater was changed, but there was no obvious damage to the internal structures of the brain after seawater acidification. Seawater acidification also led to an increase in apoptosis and a decrease in the number of proliferative cells in brain areas contacting CSF. These results indicate that the structure of CSF-contacting brain regions in medaka was affected by seawater acidification, and the brain responded to seawater acidification stress by increasing apoptosis and reducing proliferation.

Exposure to neonicotinoid pesticides induces physiological disorders and affects color performance and foraging behavior in goldfish.

We investigated the effects of neonicotinoid pesticides (NEOs) on the spontaneous swimming and foraging behavior, as well as the morphological and physiological changes of goldfish. Most fish reared in thiamethoxam (THM)-sprayed rice fields showed the scales easily peeled off, and increased ascites. Some individuals showed decreased bio-defense activity and low plasma Ca2+. Similar changes were found in the exposure test to THM (1.0 and 20.0 μg/L) and dinotefuran (1.2 and 23.5 μg/L). Next, the effects of a low concentration of THM (1.0 μg/L) on the spontaneous swimming and foraging behavior of fish were examined. Fish exposed to THM for 1 week became restless and had increased the swimming performance, especially under natural light, white LED lighting and blue LED lighting. Goldfish exposed to THM had also increased intake of shiny white beads under green LED illumination. These results indicate that the exposure to NEO, even for a short period and at low levels, not only suppressed bio-defense activities and metabolic abnormalities, but also stress response, the swimming and foraging behavior of the fish are likely to be significantly suffered.

Sex, drugs, and zebrafish: Acute exposure to anxiety-modulating compounds in a modified novel tank dive test

This study investigated the effects of anxiogenic and anxiolytic drugs on zebrafish (Danio rerio) behaviour using a modified novel tank dive test with higher walls and a narrower depth. Zebrafish were administered chondroitin sulfate, beta-carboline, delta-9-tetrahydrocannabinol (THC), ethanol, and beta-caryophyllene, and their behaviours were evaluated for geotaxis, swimming velocity, and immobility. Both anxiogenic and anxiolytic compounds generally increased bottom-dwelling behaviour, suggesting that the tank's modified dimensions significantly influence zebrafish responses. EC50 values for ethanol showed a lower threshold for velocity reduction compared to zone preference. Chondroitin sulfate uniquely caused a sex-specific increase in male swimming velocity, whereas no other sex-differences were observed with any compound. Interestingly, the presence of drug-treated fish did not alter the behaviour of observer fish, suggesting limited social buffering effects. The findings underscore the complexity of zebrafish behavioural phenotypes and highlight the need for considering tank dimensions and multiple behavioural parameters to accurately assess the effects of anxiety-modulating drugs. This study demonstrates the utility of the modified novel tank dive test in providing nuanced insights into the behavioural effects of different pharmacological agents in zebrafish.

Advancements in Research on Cichlid: Reproductive Biology, Social Structure, and Communication

The social behavior of cichlid fish emerged as a captivating subject within the realm of ichthyological research. The sociality of these aquatic organisms often encompasses a wealth of intricate elements. Within this complexity, the reproductive biology of cichlids was observed to mirror the characteristics pivotal for progeny propagation and population development. Their social structures were characterized by stringent hierarchies and occupational specialization among individuals. Communication mechanisms were found to be instrumental in ensuring the timely exchange of information across members of the species. Furthermore, population behaviors served as vital conduits, maintaining the cohesion of the aforementioned elements and securing the seamless operation of this organic system. Given these aspects, this study chose these topics as entry points for inquiry, synthesizing recent scholarly work on cichlid sociality to retrace the trajectory of research in this field. This retrospective analysis was conducted to distill clear future directions based on the examined data. The research undertaken provided a scientific reference poised to enhance further inquiry into the enigmatic subject of cichlid sociality, laying a robust foundation for both advancing the study of these fishes and fostering their conservation.

Efficacy of clove oil and rosewood oil as anesthetics on goldfish (Carassius auratus)

Anesthetics have an essential role in aquaculture operations because they minimize physical injury during various handling practices such as sampling, weighing, length measurement and tagging, which decreases stress on fish. Many fish farmers are involved in using alternative fish anesthetic agents with minimal side effects to life such as herbal essential oils. This study aims at investigating the efficacy of clove oil and rosewood oil as anesthetics on goldfish Carassius auratus. Anesthesia effect of both oils was tested in six different concentrations (i.e., 100, 150, 200, 250, 300 and 350 mg/l of water) on ten fish between 6–25 g weight and 9–14 cm length. The efficacy of both oils was assessed on the basis of the fish behavior. The induction time (min) was assessed by loss of swimming (LS), partial loss of equilibrium (PLE), final loss of equilibrium (FLE), and medullar collapse (Mc). The fish were observed for balance and response to a tactile stimulus in each treatment. Both clove oil and rosewood oil contributed well as anesthetics as they caused loss of equilibrium and swimming ability in the goldfish. In contrast, clove oil generated more rapid induction, prolonged recovery, and a narrow margin of safety. Fish farmers should use natural and environment friendly anesthetic agents instead of chemical ones, as they may alter negatively the growth and health of fish.

Contextual fear conditioning in zebrafish: Influence of different shock frequencies, context, and pharmacological modulation on behavior

Contextual fear conditioning is a protocol used to assess associative learning across species, including fish. Here, our goal was to expand the analysis of behavioral parameters that may reflect aversive behaviors in a contextual fear conditioning protocol using adult zebrafish (Danio rerio) and to verify how such parameters can be modulated. First, we analyzed the influence of an aversive stimulus (3 mild electric shocks for 5 s each at frequencies of 10, 100 or 1000 Hz) on fish behavior, and their ability to elicit fear responses in the absence of shock during a test session. To confirm whether the aversive responses are context-dependent, behaviors were also measured in a different experimental environment in a test session. Furthermore, we investigated the effects of dizocilpine (MK-801, 2 mg/kg, i.p.) on fear-related responses. Zebrafish showed significant changes in baseline activity immediately after shock exposure in the training session, in which 100 Hz induced robust contextual fear responses during the test session. Importantly, when introduced to a different environment, animals exposed to the aversive stimulus did not show any differences in locomotion and immobility-related parameters. MK-801 administered after the training session reduced fear responses during the test, indicating that glutamate NMDA-receptors play a key role in the consolidation of contextual fear-related memory in zebrafish. In conclusion, by further exploring fear-related behaviors in a contextual fear conditioning task, we show the effects of different shock frequencies and confirm the importance of context on aversive responses for associative learning in zebrafish. Additionally, our data support the use of zebrafish in contextual fear conditioning tasks, as well as for advancing pharmacological studies related to associative learning in translational neurobehavioral research.

Fish Behavior, Mortality, Diet, and Movement Following a Monsoonal Spate in the San Juan River, Utah, USA

Fish Behavior, Mortality, Diet, and Movement Following a Monsoonal Spate in the San Juan River, Utah, USA

Kiss1 kisspeptin of bony fish and mammalian kisspeptin analogs enhance the communicative behavior of <i>Danio rerio</i> induced by social isolation

BACKGROUND: Rodents are often used as a social isolation model. This study investigated the effects of social isolation on Danio rerio. These animals form groups and social hierarchies and exhibit complex social interactions similar to rodents. The expression of some brain genes of fish reared in isolation was found to be different from individuals reared in a group. AIM: This study aimed to investigate the effect of kisspeptins on the social behavior of Danio rerio in social isolation. MATERIALS AND METHODS: Fish were placed in 200-mL measuring cups for 48 h. After the social isolation period, bony fish kisspeptins and mammalian kisspeptin analogs were administered, and their effects were tested. The animal was placed in 1-L individual tanks for 15 min and then in the tank with a glass partition, behind which are a group of congeners. Fish were allowed to approach or swim away from the partition. Two patterns were used to assess behavior: latency time and number of swims to the partition. RESULTS: Compared with the control group with fish kept in social isolation, reliable differences were observed: The number of swims to the partition after isolation was 1.3 times higher than that in the control group (p 0.05). After the administration of bony fish kisspeptins Kiss1 and Kiss2, no significant changes in the number of swims to the partition were observed. Moreover, after the administration of KS6 and KS10, the number of swims to the aquarium partition increased 1.6 times (p 0.01) and 1.8 times (p 0.001), respectively. After the administration of the comparison drug oxytocin, the number of swims to the aquarium partition increased 1.6 times (p 0.01) compared with that in the untreated isolated group. The latency time of swimming to the partition increased 2.4 times in the untreated isolated group compared with the control group (p 0.001). Latency time decreased 2.3 times in the group administered with oxytocin compared with the untreated isolated group (p 0.001). In the group administered with Kiss1, the latency time decreased 2 times (p 0.001) compared with that in the untreated isolated group. The latency time decreased 5 times (p 0.001) after KS10 administration and 3.4 times (p 0.001) after KS6 administration compared with that in the untreated isolated group. CONCLUSIONS: Thus, social isolation in Danio rerio reduces communicative behavior. Analogs of mammalian kisspeptin, such as Kiss1, of bony fish and oxytocin normalize the communicative behavior of fish after a period of social isolation to the level of the control group.

Diel rhythms of fish frequentation in a temperate mesophotic antipatharian forest and sleeping behaviour of the red swallowtail perch Anthias anthias (Linnaeus, 1758)

A 21-day continuous monitoring of a highly tridimensional forest of the black coral Antipathella subpinnata (Ellis and Solander 1786) was carried out in the NW Mediterranean Sea at 63 m depth using an autonomous lander to investigate the diel short-term dynamics of the vagile fauna associated to the forest. The survey allowed to assess several aspects of the forest attractiveness and its use, especially by the ichthyofauna, including (i) the diversity and shifts of the fish community inhabiting three layers of the environment (seafloor, canopy, water column) between four light phases (dawn, day, dusk, night), (ii) the diel rhythm in forest use of the red swallowtail perch Anthias anthias (Linnaeus 1758) and its sleeping behaviour in terms of fidelity towards resting sites, duration of rests, and awakenings triggers, and, finally, (iii) the influence of biotic and abiotic variables on the fish behaviour. Considering that, so far, only spot censuses have been carried out in these habitats, this study provides a dynamic approach to the study of biodiversity in temperate mesophotic coral forests and offers an insight into the functioning of these complex and vulnerable ecosystems.

Existing datasets uncover complex interactions driving catches of a data‐poor recreational fishery in South Australia

AbstractUnderstanding drivers of effort and catch is important for sustainable management of recreational fisheries. For the Pipi (Latona deltoides) fishery in South Australia as a case study, publicly available datasets on fisher demography, market forces and internet connectivity improved understanding of fisher motivations and capabilities, identified different historical periods in the fishery and addressed temporal gaps in effort and catch estimates from on‐site surveys. Most variables were correlated with recreational effort and catch estimates from on‐site surveys and principal component analysis identified 2013–2014, 2015–2018 and 2019–2022 as distinct periods in the Pipi fishery. Results corroborated studies and anecdotal information that suggested declining availability and higher prices of local, commercially caught Pipi, and reduced imports of bivalves from Asia that previously supplied the South Australian bait market. Reduced availability and higher prices of Pipi likely motivated recreational fishers to gather their own bait to increase catch over the years. Similarly, increased internet and smartphone access and increased numbers of utility vehicles aided recreational catch efficiency of Pipi. Effective management of recreationally harvested resources requires understanding of external processes that drive fisher motivations and capabilities, particularly for stocks that are shared among fisheries. The need for improved data on fisher behaviour for management of recreational fisheries can be addressed by leveraging external information from available datasets. We recommend that the temporal gap between surveys should be less than 5 years, supplemented by analysing behavioural information collected from fishers during interviews.

Fish 3D Locomotion app: a user-friendly computer application package for automatic data calculation and endpoint extraction for novel tank behavior in fish.

This paper introduces the Fish 3D Locomotion app (F3LA), a Python-based, Graphical User Interface (GUI)-equipped tool designed to automate behavioral endpoint extraction in zebrafish locomotion assays. Building on our previous work, which utilized a specialized aquatic tank with a mirror and a single camera for fish movement tracking in three dimensions, F3LA significantly enhances data processing efficiency. Its accuracy was tested by reanalyzing and comprehensively comparing the calculated data with the previously published data from prior publications. From the comparison results, 90% of endpoints showed a similar statistical difference result. These minor differences were due to the different starting points for the dataset and updated calculation formulas that are implemented in F3LA. In addition, shoaling area or shoaling volume calculations are also included in F3LA as a new feature that can serve as sensitive indicators of social cohesion, group dynamics, or stress responses, offering insights into neuropsychological conditions or the effects of pharmacological interventions. Furthermore, F3LA offers a marked improvement over manual operations, being at least five times faster, while maintaining consistent accuracy as it reduces human-induced errors, ensuring a higher degree of reliability in the results. Finally, the potency of F3LA was tested to evaluate the toxicities of 14 rare earth elements (REEs) to the adult zebrafish behaviors. Based on the results, our findings suggested that each tested REE altered fish behaviors in different patterns and magnitudes to each other. However, among the tested light rare earth elements (LREEs), neodymium was demonstrated to cause more relatively severe behavior alterations than other LREEs, indicated by the statistically higher value of entropy (0.2695 ± 0.04977 (mean with a standard deviation)) than the control group (0.2352 ± 0.05896). Meanwhile, in terms of heavy rare earth elements (HREEs), erbium seemed to lead to more distinct behavior toxicities than other HREEs, which was shown by the statistically lower level of fractal dimension (2.022 ± 0.3412) than the untreated group (2.255 ± 0.1661). Taken together, F3LA's development marks a significant advance in high-throughput toxicological and pharmacological assessments in zebrafish, leveraging three-dimensional locomotion data for a more comprehensive analysis of fish behavior performance, providing a significant contribution to research in various fields.

Seasonal and Daily Movement Patterns by Wels Catfish (Silurus glanis) at the Northern Fringe of Its Distribution Range

Fish behavior often varies across a species’ distribution range. Documenting how behaviors vary at fringes in comparison to core habitats is key to understanding the impact of environmental variation and the evolution of local adaptations. Here, we studied the behavior of Wels catfish (Silurus glanis) in Lake Möckeln, Sweden, which represent a European northern fringe population. Adult individuals (101–195 cm, N = 55) were caught and externally marked with data storage tags (DSTs). Fifteen DSTs were recovered a year after tagging, of which 11 tags contained long-term high-resolution behavioral data on the use of vertical (depth) and thermal habitats. This showed that the catfish already became active in late winter (<5 °C) and displayed nocturnal activity primarily during summer and late autumn. The latter included a transition from the bottom to the surface layer at dusk, continuous and high activity close to the surface during the night, and then descent back to deeper water at dawn. During the daytime, the catfish were mainly inactive in the bottom layer. These behaviors contrast with what is documented in conspecifics from the core distribution area, perhaps reflecting adaptive strategies to cope with lower temperatures and shorter summers.

Food odors elicit feeding behavior through the activation of the olfactory system in blunt snout bream (Megalobrama amblycephala)

Olfaction plays an important role in the survival and reproduction of various organisms. Aside from being a nutrient, in many fish species, amino acids also function as attractants to induce feeding behaviors. As the herbivorous fish, blunt snout bream (Megalobrama amblycephala) commonly consumes an aquatic plant, Hydrilla verticillata. Here, we studied the effect of food odors on the feeding behavior of blunt snout bream using a mixture of amino acids and H. verticillata extract. The behavioral and electro-olfactogram tests demonstrated that the mixture of amino acids and H. verticillata extract induced an attractive reaction and olfactory response in blunt snout bream, respectively. Through Western blotting and immunohistochemical analyses, we confirmed that ciliated and microvillus neurons are distributed on the olfactory placode. The results of phospho-extracellular regulated protein kinases (pERK) showed that a large number of microvillus and ciliated neurons were activated under the stimulation of 10−5 mol/L amino acid mixture and 0.005× H. verticillata extract. The calcium signal imagery demonstrated that the nerve signals of the olfactory bulb were activated by the food odors. The quantitative real-time PCR (qPCR) analysis revealed significant changes in the expression of representative olfactory receptor genes in the olfactory bulb and brain of blunt snout bream upon stimulation with food odor. Collectively, these results provided evidence and preliminary explanations for the mediating role of olfaction in the feeding behavior of fish.

Movement patterns of Murray cod (Maccullochella peelii) and golden perch (Macquaria ambigua) in a northern Murray–Darling Basin dryland river

Context Dryland rivers are unique ecosystems, where drought and flood play an important role in shaping the ecosystem. River regulation has altered the natural flow regime in many of these systems, affecting migration cues and connectivity for many species. Aims To quantify the discharge-related movements of Murray cod and golden perch within the Condamine–Balonne River subject to differing levels of river regulation. Methods We quantified flow regime variability, river regulation and fish movement to develop generalised additive mixed models to predict movement probability for Murray cod and golden perch. Results Both species showed strong positive relationships between discharge and movement. Murray cod did not show any association with river regulation; however, medium-sized individuals were significantly more likely to move than were smaller or larger fish. Golden perch movements varied among levels of regulation, were more likely to move as body weight increased and showed seasonality of movement, moving less during winter. Conclusions This study presents the largely unobserved movement behaviours of fish across a gradient of river regulation and environmental conditions in the northern Murray–Darling Basin. Implications This information is valuable for informing policy and management decisions that may affect species’ life-history requirements in analogous river systems.

Soundscape characteristics of RAS tanks holding Atlantic salmon (Salmo salar) during feeding and feed withdrawal

Behavioural monitoring can provide crucial information on welfare and feeding in aquaculture. Passive acoustic monitoring of behaviour can be particularly useful in recirculating aquaculture systems (RAS), as they often have turbid water that impairs visual monitoring. Currently, little is known about the sounds that make up the soundscapes in RAS tanks holding Atlantic salmon (Salmo salar). In this study, hydrophones were used to continuously record the soundscape in eight single tank RAS holding Atlantic salmon parr for 15 days, with the fish in four of the tanks being fasted by feed withdrawal for five days from the sixth to the tenth day. The results show that soundscapes in RAS tanks are affected by feeding. Two main sound sources were identified during feeding in RAS tanks, one related to pellets delivery and the other to fish behaviour. The sound of pellets hitting the water surface had energy concentrated at frequencies between 1.7 and 4.0 kHz, with peak frequency decreasing and amplitude increasing with increasing number of pellets hitting simultaneously. The feeding sounds of Atlantic salmon had energy concentrated at frequencies between 6.5 and 9.4 kHz.More complex soundscapes were recorded during feeding events. These were characterized by variations in amplitude and frequency that have been described by using acoustic indexes in RAS tanks for the very first time. The Acoustic Complexity Index (ACI), the Acoustic Entropy Index (H) and the Normalized Difference Soundscape Index (NDSI) showed distinct changes in the soundscape related to feeding events; ACI increased while H and NDSI decreased compared to the times in between scheduled feeding times. The sound types identified in this study and the outcomes of the acoustic indices indicate a possibility to monitor system performance as well as fish behaviour in the tank soundscapes in RAS. Soundscape monitoring can contribute to match feeding closer to fish appetite, improve water quality, and reduce risks that deviations in the system performance can have on fish welfare during production.

Bioaccumulation, transfer, and impacts of microplastics in aquatic food chains

Plastics have become a pervasive global contaminant since the mid-20th century, causing harm to organisms at all levels. Preventative measures to reduce plastic pollution and awareness-raising campaigns about the damaging effects of plastic debris on the environment and its inhabitants are crucial; however, most plastic assessments focus on singular trophic levels. Microplastics, tiny plastic particles ranging from 25 μm to 5 mm, have emerged as a widespread form of pollution found in ecosystems worldwide. They can enter the environment directly or through the breakdown of larger plastic debris and are thought to be mistaken for food by foraging animals. This leads to microplastics circulating through ecosystems via direct and indirect consumption, ultimately impacting even higher-order predators. Here, we assess the impacts of microplastics on Chlorophyll a concentrations, algal community structure, copepod survivorship, and fish behavior in experimental trials, in addition to simulated top-predator foraging success on plastic-exposed fish. Our results indicate that microplastics have detrimental effects on algal growth and copepod survival. We also observed the trophic transmission of small plastic spheres from copepods to fish predators, highlighting a concerning pathway for microplastic pollution within aquatic ecosystems, where fish consumed plastics through direct and indirect means. Primary consumers, like copepods, face dual pressures from top-down forcing, as they are preferred over plastic particles as food sources, and bottom-up resource depletion, as algal food supplies can be limited by microplastic exposure. Our findings demonstrate the system-wide impacts that can occur when microplastics are included in food chains and underscore the urgent need for comprehensive strategies to mitigate the entry of plastic debris into aquatic ecosystems.