Cassia Regina Ramos Gonzaga1
Cristiano Schetini de Azevedo2*Helen Colbachini3Laura Chrispim Reisfeld3Fabiana Lúcia André Padilha3Rafael Caprioli Gutierrez3
Cristiane Schilbach Pizzutto1,4- 1Faculdade de Medicina Veterinária e Zootecnia, Universidade de São Paulo, São Paulo, Brazil
- 2Laboratório de Zoologia dos Vertebrados, Instituto de Ciências Exatas e Biológicas, Departamento de Biodiversidade, Evolução e Meio Ambiente, Universidade Federal de Ouro Preto, Ouro Preto, Brazil
- 3Aquário de São Paulo, São Paulo, Brazil
- 4Laboratório de Ecologia e Evolução, Instituto Butantan, São Paulo, Brazil
Introduction: Freshwater stingrays of the genus Potamotrygon are endemic to South America and increasingly maintained in aquaria worldwide, yet welfare studies on these species remain limited. Environmental enrichment, particularly feeding strategies, is recognised as stimulating natural behaviours and improving welfare in captivity.
Methods: This study assessed the behavioural responses of Potamotrygon motoro, P. orbignyi, and P. falkneri to three feeding methods designed to impose different levels of access difficulty: (i) scattered food at the surface (easy), (ii) food buried in the substrate (intermediate), and (iii) food placed inside perforated bottles (difficult). Research was conducted at the São Paulo Aquarium, where eight adult females were housed in a mixed-species tank. Over three weeks, behaviours were recorded using scan sampling at 45-second intervals and analysed using Generalised Linear and Generalised Linear Mixed Models.
Results: Stingrays spent significantly more time interacting with food under all enrichment treatments than under standard feeding, and exhibited reduced inactivity and increased swimming. Enriched conditions elicited species-typical behaviours such as substrate disturbance during foraging.
Discussion: Overall, the findings demonstrate that feeding challenges, as they align with elasmobranch behavioural ecology, promote behavioural diversity and indicators of improved welfare. Incorporating such enrichment into routine husbandry may enhance the quality of life in captive stingrays and provide evidence-based guidance for welfare practices in aquaria and zoological institutions.
1 Introduction
The maintenance of animals in human care, whether in zoological or aquatic environments, represents a fundamental commitment to animal welfare and species conservation. The evaluation and optimisation of ex situ environmental conditions are crucial to ensure that animals not only survive but also thrive, exhibiting their natural behavioural repertoires and demonstrating positive welfare indicators (Young, 2003; Monreal-Pawlowsky et al., 2021). However, the field of aquatic animal welfare, particularly that of elasmobranchs, presents a critical gap, as many ray and shark species face significant threats in their natural habitats, making aquarium populations key components of conservation and education programs (Colbachini et al., 2021; Barros et al., 2024).
In this context, Environmental Enrichment (EE) stands out as one of the most effective tools for promoting animal welfare in artificial environments (Shepherdson, 1998; Monreal-Pawlowsky et al., 2021). The effectiveness of EE, however, critically depends on a deep understanding of the natural history, ecology, and specific behavioural needs of each species (Corcoran, 2015; Monreal-Pawlowsky et al., 2021; Brereton and Rose, 2022; Smith et al., 2025). This implies moving beyond generic approaches to develop goal-oriented enrichment strategies that aim to elicit biologically relevant behaviours (Dawkins, 1990; Young, 2003; Alligood and Leighty, 2015; Näslund and Johnsson, 2016; Monreal-Pawlowsky et al., 2021).
In artificial environments, feeding is often simplified, offered at predictable times, and presented in a manner that requires no effort or skill from the animal to acquire (Barros et al., 2024). This lack of challenge can lead to short feeding times and the development of undesirable behaviours (Bassett and Buchanan-Smith, 2007). Studies have shown that variation in the timing and presentation method of food, especially when it involves a challenge to obtain it, stimulates natural foraging and feeding behaviours, resulting in a significant improvement in welfare (Young, 1997; Brereton, 2020; Waasdorp et al., 2021).
In the specific case of benthic rays, such as those of the genus Potamotrygon, their natural foraging behaviours involve substrate excavation with their pectoral fins, using water jets from the mouth to unearth prey, and activation of cephalic lobes for suction (Sasko et al., 2006; Collins et al., 2007; Ajemian and Powers, 2012; Barros et al., 2024). Replicating these strategies in captivity through challenging feeding enrichment is, therefore, ecologically relevant and fundamental for the welfare of these species (Brown et al., 2003; Alderman and Clayton, 2021; Barros et al., 2024).
Elasmobranchs demonstrate problem-solving abilities, behavioural flexibility, and even memory retention in visual and spatial discrimination tasks (Kuba et al., 2010; Thonhauser et al., 2013; Daniel et al., 2021; Brunet et al., 2023; Shen et al., 2023). For example, the South American freshwater stingrays (Potamotrygon motoro) use vision for spatial orientation and can be trained in cognitive studies with visual stimuli, distinguishing colours, shapes, and contrasts (Schluessel and Bleckmann, 2005; Schluessel et al., 2015; Schluessel and Ober, 2018; Daniel et al., 2021). This cognitive complexity suggests that EE should not only be physically but also mentally stimulating, providing opportunities to exercise these capacities (Carlstead and Shepherdson, 1994). The incorporation of challenges in food acquisition, which require manipulating objects or overcoming obstacles, can serve as valuable cognitive enrichment (Kuba et al., 2010). Furthermore, responses to enrichment can vary individually, reflecting differences in personality or behavioural syndromes, highlighting the importance of personalised approaches and continuous evaluation (Corcoran, 2015; Monreal-Pawlowsky et al., 2021; Harris et al., 2024).
Freshwater stingrays of the genus Potamotrygon, endemic to South America, are increasingly common in aquaria worldwide (Daniel et al., 2021). Despite their growing presence in zoological institutions, welfare studies focused on these specific species, given their ecology and complex behaviours, remain limited. Recognising this gap, the present study aimed to evaluate the behavioural responses of three South American freshwater stingray species: the South American freshwater stingray (Potamotrygon motoro), the smooth-backed river stingray (Potamotrygon orbignyi), and the large-spotted river stingray (Potamotrygon falkneri) to various feeding enrichment strategies. We hypothesised that the more challenging feeding strategies would be more effective in increasing foraging.
2 Materials and methods
2.1 Animals, housing, and maintenance
All procedures performed in this study were approved by the Ethics Committee on Animal Use of the School of Veterinary Medicine and Animal Science, University of São Paulo (CEUA/FMVZ; protocol no. 2179230320).
The present study was conducted at the São Paulo Aquarium, located in São Paulo, southeastern Brazil, (23°35′36.5′′S 46°36′51.1′′W) between January and June 2021. Eight specimens of stingray from the genus Potamotrygon were observed: four South American freshwater stingray (P. motoro), two smooth back river stingray (P. orbignyi), and two largespot river stingray (P. falkneri). All individuals were adult female stingray and had inhabited a single tank (2,2 m deep, 3,5 m wide, and 6,5 m long, holding 50,000 l of water) for two years. This tank was shared with various teleost fish species.
The institution carried out all animal husbandry and tank maintenance. Feeding consisted of shrimp, 3 cm x 1 cm strips of fish (tilapia, pacu, piranha, catfish), and earthworms, offered three times a week, always at 8 AM and 2 PM. This feeding regime represents the standard, established diet for these animals within the institution. Food was provided directly to each animal by a diver, a routine practice. All food items used were already part of the animals’ established diet, as determined by the institution.
2.2 Experimental protocol
The study was divided into four treatments based on the difficulty of acquiring the food offered via EE items. The first treatment involved collecting behavioural data from the stingrays before the provision of EE items (Before treatment: the baseline period, during which no enrichment was provided, and regular feeding activities continued as usual). The EE treatment was divided into three conditions: when food was scattered directly onto the tank surface, the challenge level was considered easy (Scattered treatment) (Figure 1A). Because the tank was shared with several other fish species, some of the food distributed throughout the tank by scattering was consumed by fish in the water column, with stingrays feeding on the portion that reached the tank bottom. At the intermediate level, food was buried at six different points on the tank bottom (Buried treatment) (Figure 1B). Finally, the difficult level involved offering food inside seven perforated plastic bottles, which allowed food to be extracted only through suction by the stingrays (Bottle treatment) (Figure 1C). The bottles were lowered from the top of the tank, attached to a weight that anchored them to the bottom. For feeding during challenge intermediate (Buried) and difficult (Bottle), priming food was first offered to the other fish in the upper water-column regions to reduce interference from them with the food explicitly provided to the stingrays.
Figure 1. Challenge levels for food acquisition by stingrays in an environmental enrichment study. (A) Easy level (Scattered treatment): Food is dispersed directly onto the water surface. (B) Intermediate level (Buried treatment): Food is placed at six points beneath the tank substrate. (C) Difficult level (Bottle treatment): Food is inserted into seven perforated plastic bottles, which the stingrays must extract using suction.
Observations were conducted over three consecutive weeks, with all three feeding treatment levels alternated within weeks. The order of item presentation was randomised via weekly draws. Behavioural data were collected using scan sampling, with instantaneous recordings made every 45 seconds (Bateson and Martin, 2021; Naguib et al., 2023). Behavioural data were collected across 48 sessions per level, each lasting 30 minutes, resulting in 24 hours of observation per level (96 hours in total). The Before treatment condition was recorded during the three-week experimental period before the implementation of any EE.
For behavioural data collection, the following ethogram was employed, based on 20 hours of preliminary observations and published studies on the species (Garrone-Neto and Sazima, 2009) (Table 1).
Table 1. Ethogram of Potamotrygon stingray species (South American freshwater stingray, Potamotrygon motoro; smooth back river stingray, Potamotrygon orbignyi; and largespot river stingray, Potamotrygon falkneri) used in the evaluation of the effects of four treatments (before EE; easy EE: scattered food; intermediate EE: buried; difficult EE: bottle) on the behaviour of individuals housed at the São Paulo Aquarium.
2.3 Statistical analysis
To investigate the behavioural responses of the animals to different food enrichment items, statistical analyses were conducted using Generalised Linear Models (GLMs) and Generalised Linear Mixed Models (GLMMs). All analyses and visualisations were performed in R (version 4.5.1) (R Core Team, 2025) and RStudio (version 2025.09.2 + 418) (RStudio Team, 2025), employing key packages from the Tidyverse for data manipulation and graphical output (Wickham et al., 2019).
Model fitting was carried out using the glmmTMB package (Brooks et al., 2017). For each behavioural response, two primary model structures were considered: a GLMM with a random intercept for Individual (Response ~ Treatment + (1|Individual)) to account for individual-level variability, and a simpler GLM without a random effect (Response ~ Treatment). The count of behaviours served as the response variable, with Treatment (before enrichment, bottle, buried, and scattered items) as the fixed effect.
A systematic, data-driven approach was used to select the most appropriate model for each behaviour. Various conditional distribution families were evaluated, including Negative Binomial (Types 1 and 2), Poisson, Zero-Inflated Poisson (ZIP), Zero-Inflated Negative Binomial (ZINB2), and Gaussian (Zuur et al., 2009). The optimal model was selected based on the lowest Akaike Information Criterion (AIC) value (Bolker et al., 2009). Models with convergence issues or unstable parameter estimates (e.g., non-positive-definite Hessian matrices) were excluded. For behaviours with complete data separation (e.g., zero counts in a treatment level), parameter estimates were considered unreliable and excluded from quantitative interpretation.
Model assumptions, including collinearity and the distribution of residuals, were rigorously assessed. Collinearity was evaluated using the Generalised Variance Inflation Factor (GVIF), indicating negligible collinearity among predictors (GVIF ≈ 1) (Fox and Weisberg, 2019). Selected error distributions mitigated issues such as overdispersion and excess zeros.
Post-hoc analyses included the computation of estimated marginal means (EMMs) for Treatment levels using the emmeans package (Lenth, 2025), with pairwise comparisons adjusted using Tukey’s method. Best Linear Unbiased Predictors (BLUPs) were extracted for the Individual random effect in GLMMs to provide individual-level deviations from the population mean, adjusted for Treatment (Henderson, 1975; Zuur et al., 2009; De Water et al., 2017; Hoarau and Dumont, 2023). BLUPs were presented on a logarithmic scale and back-transformed to counts, interpreted as percentage deviations from the overall mean. Manual pairwise comparisons of BLUPs were conducted to further investigate individual differences.
Visual exploration of behavioural distributions across Treatment conditions was conducted using violin plots with ggplot2 (Wickham, 2016) overlaid with boxplots indicating medians, interquartile ranges, and potential outliers, for selected behaviours (S, IN, SU, PR, MFR, and O). Panels of violin plots were assembled using the patchwork package (Pedersen, 2025). The violin plot for PB is not presented because it occurs exclusively in the Bottle treatment; the corresponding model results are reported in the text.
3 Results
The descriptive analysis revealed variation in the frequency of behaviours across treatments (mean ± SEM). Before treatment, the most frequently recorded behaviours were Inactive (IN: 187.37 ± 9.18) and Swimming (S: 161.1 ± 7.91), while Other behaviours (O: 0.37 ± 0.26) and Pushing the bottle (PB: 0.00 ± 0.00) were absent or near zero. For the Scattered treatment (easy), Inactive (IN: 52.13 ± 13.50) and Swimming (S: 50.50 ± 2.77) behaviours predominated, with Other behaviours (O: 0.63 ± 0.18) remaining at minimal levels. In the Buried condition (intermediate), Swimming (S: 41.00 ± 2.67) and Sucking up the food (SU: 37.75 ± 5.27) were most common, followed by Moving the frontal region of the discoid body (MFR: 23.38 ± 1.24), while Other behaviours (O) were not recorded. Under the Bottle treatment (difficult), Swimming remained high (S: 32.37 ± 2.83), but Sucking up the food (SU: 42.62 ± 6.44) and Pushing the bottle (PB: 27.25 ± 1.72) became more prominent, whereas behaviours such as inactive (IN: 7.25 ± 0.96), Other behaviours (O: 0.50 ± 0.50), and the category Not visible (NV: 1.13 ± 0.79) were rarely expressed. Across treatments, behaviours such as Other behaviours (O) consistently occurred at very low levels, and Pushing the bottle (PB) was absent in three of the four treatments (Before, Scattered, and Buried treatments).
Analysis of the GLM and GLMM models revealed several significant differences in behaviours across treatments; however, the Pushing the bottle (PB) behaviour, which was exclusively recorded in the Bottle treatment, was not included in the models, and only descriptive statistics were provided for it (Table 2; Figure 2). Stingrays spent less time Swimming (S) in the Bottle and Buried treatments than in the Before treatment, whereas the Scattered treatment did not affect Swimming. Inactive (IN) behaviour decreased across all enrichment treatments. Sucking up the food (SU) and Pushing another stingray (PR) behaviours increased under all enrichment treatments, although some pairwise comparisons were not statistically significant. Moving the frontal region of the discoid body (MFR) increased under all enrichment treatments, with most post-hoc comparisons significant. Other behaviours (O) increased only under the Scattered treatment, and Not visible (NV) showed no significant changes across treatments (Table 2; Figure 2).
Table 2. Summary of GLM and GLMM results for each behaviour across the Before and EE treatments.
Figure 2. Violin plots with embedded boxplots illustrating the distributions of behavioural responses of the Potamotrygon stingrays across different treatments, as analysed by Generalised Linear Models (GLMs) and Generalised Linear Mixed Models (GLMMs). The treatments (Before, Bottle, Scattered, and Buried) represent different food enrichment strategies. Within each boxplot, the central line indicates the median, the box delineates the interquartile range (IQR, from the 25th to the 75th percentile), and the whiskers extend to 1.5 times the IQR from the box edges. Outliers are depicted as individual points beyond the whiskers. The violin shape represents the kernel density estimation of the data distribution.
Individual differences in the studied behaviours were assessed using Best Linear Unbiased Prediction (BLUP) values, expressed as percentage deviation from the population mean (Figure 3). For Inactive (IN), most individuals exhibited relatively modest deviations, with R1 showing the largest positive deviation (17.5%) and R8 the largest negative deviation (12.7%). Sucking up the food (SU) exhibited considerable variation, with individuals R1 to R5 performing above average (e.g., R4 at +34.9%), while R6 to R8 were markedly below (e.g., R8 at -37.7%). Pushing another stingray (PR) similarly revealed substantial individual variation, with R1-R3 below average (e.g., R1 at -42%) and R4-R8 generally above (e.g., R6 at +44.9%). Notably, Not visible (NV) displayed highly extreme individual differences. While R1-R5 were below the mean (approximately -25%), individuals R6, R7, and R8 demonstrated exceptionally high positive deviations, reaching up to 1,746,089.5% above the mean. These extreme VIF values reflect near-zero variance in the corresponding random-effect levels rather than biological differences; therefore, they were visually truncated at +100% in Figure 3, with their full magnitudes annotated to preserve quantitative information. All other behaviours not presented here did not show significant individual differences.
Figure 3. Individual differences (BLUPs: Best Linear Unbiased Prediction) in three behaviours (IN: Inactive, SU: Sucking up the food, PR: Pushing another stingray) and for the category Not Visible (NV) for eight individuals (R1-R8) of Potamotrygon stingrays, expressed as percentage deviation from the mean. Each lollipop chart illustrates the estimated individual-specific BLUPs for a given behaviour, indicating the extent to which an individual’s performance deviates from the population mean (red dashed line at 0%). Green points indicate performance above the mean, while red points indicate performance below the mean. Values ranging from -100% to +100% are plotted within the standard scale. For extreme BLUPs, values below -100% or above +100% are visually truncated at these limits to maintain scale consistency across all behaviours. Truncated points are marked with triangles (upward for values > 100%, downward for values < -100%), and their actual percentage deviation is numerically annotated alongside.
4 Discussion
The present study investigated the effects of different feeding enrichment strategies on the behaviour of freshwater stingrays of the genus Potamotrygon in captivity, focusing on the species P. motoro, P. orbignyi, and P. falkneri. The results clearly demonstrate that introducing challenges to food acquisition significantly influences the behavioural repertoire of stingrays, promoting greater expression of natural foraging behaviours and reducing inactivity. These findings corroborate the growing literature emphasising the importance of EE for the welfare of aquatic species (Näslund and Johnsson, 2016; Monreal-Pawlowsky et al., 2021), and provide valuable insights for the broader management of elasmobranchs under human care.
One of the most prominent results was a significant reduction in Inactivity (IN) and general Swimming (S) in stingrays subjected to enrichment treatments (Scattered, Buried, and Bottle). In contrast, behaviours directly related to seeking and obtaining food, such as Sucking up the food (SU) and Moving the frontal region of the discoid body (MFR), substantially increased. The decrease in inactivity is a strong indicator of improved welfare, as an impoverished environment can lead to apathy and repetitive, purposeless behaviours (Dawkins, 1990; Mason et al., 2007). The replacement of passive behaviours with more active and foraging activities suggests that the stingrays are engaging more with their environment in a biologically relevant manner, a central goal of EE (Young, 2003; Monreal-Pawlowsky et al., 2021). Such behavioural shifts are consistent with findings in other elasmobranch taxa, in which stimulation of foraging and activity has been linked to improved welfare indicators (Colbachini et al., 2021; Monreal-Pawlowsky et al., 2021; Harris et al., 2024).
The behaviour Sucking up the food (SU), which involves undulating the disc and disturbing the substrate to expel sediment and access food, was consistently elevated across all enrichment treatments. This behaviour, along with Moving the frontal region of the discoid body (MFR), which also showed an increase, is ecologically relevant for Potamotrygon stingrays, mimicking hunting and foraging tactics observed in their natural environment (Garrone-Neto and Sazima, 2009). The ability of enrichment items to elicit these specific behaviours is a positive sign that the interventions are aligned with the species’ natural history. Barros et al. (2024) observed a similar effect in cownose rays (Rhinoptera bonasus), in which feeding enrichment stimulated foraging behaviours, demonstrating that manipulating the presentation of food can be a powerful tool for promoting natural behaviours. This cross-species consistency underscores the general applicability of feeding enrichment principles across elasmobranchs.
The variation in food access difficulty levels resulted in different behavioural patterns. Although the easy food treatment (Scattered) increased Sucking up the food (SU), the intermediate (Buried) and difficult (Bottle) treatments were particularly effective in stimulating SU and Moving the frontal region of the discoid body (MFR), requiring greater effort and potentially greater problem-solving. The exclusive interaction with the Pushing the bottle (PB) behaviour in the Bottle treatment is a strong indication that the stingrays actively engaged in accessing food, demonstrating persistence and flexibility. This requirement to “work” for a reward represents an essential aspect of cognitive enrichment, potentially enhancing the animals’ welfare (McGowan et al., 2010; Vasconcellos et al., 2012; Barros et al., 2024). The ability of elasmobranchs, such as Potamotrygon castexi, to solve problems to access food, such as extracting food from a tube (Kuba et al., 2010), supports the idea that enrichment requiring cognitive and physical effort is beneficial and should be encouraged. Daniel et al. (2021) also highlight the cognitive complexity of P. motoro in visual discrimination and problem-solving tasks. Collectively, these findings contribute to the growing recognition that elasmobranchs are capable of sophisticated cognitive processing and can benefit from cognitively demanding enrichment.
Interestingly, we observed an increase in Pushing another stingray (PR) behaviour across all enrichment treatments. This behaviour can be interpreted as an indication of resource competition, especially during feeding. Barros et al. (2024) also reported an increase in agonistic behaviours in cownose rays with feeding enrichment, suggesting that the distribution of enrichment items, particularly in groups, should be carefully planned to mitigate excessive competition and potential injuries. Stocking density and available space are also important factors to consider, as Greenway et al. (2016) noted for thornback rays (Raja clavata), where increased group size elevated stereotypic behaviours. Such social dynamics should be considered not only in freshwater but also in marine elasmobranch species, where hierarchical interactions may similarly influence access to enrichment resources.
Individual stingrays exhibit variation in their responses to enrichment. The observed differences in Inactivity (IN), Sucking up the food (SU), and Pushing another stingray (PR) suggest that not all individuals respond in the same way. For example, R1 displayed the highest positive deviation for Inactivity (IN), R8 the highest negative deviation, and R4 the highest positive deviation for Sucking up the food (SU). These individual differences highlight the importance of personalised management approaches and continuous observation to meet each animal’s needs (Monreal-Pawlowsky et al., 2021; Smith et al., 2025). Moreover, the consistent behavioural variation among individuals is indicative of stable personality traits or behavioural syndromes (Dall et al., 2004; Watters and Powell, 2012; Corcoran, 2015) and warrants dedicated studies to formally characterise stingray personality and investigate how it influences responses to enrichment. Understanding personality variation could also provide a framework for predicting enrichment outcomes across elasmobranch taxa.
Although the present study did not directly focus on space utilisation, the promotion of substrate foraging behaviours, especially in the Buried and Bottle treatments (bottles were anchored to the bottom), encouraged exploration and the use of different tank areas. Rays are epibenthic and spend most of their time partially buried in the substrate (Nottage and Perkins, 1983; Greenway et al., 2016; Hart et al., 2022). These previously cited studies demonstrate that space utilisation is a valuable welfare indicator for elasmobranchs and that the strategic distribution of feeding enrichment can influence the use of different depths and quadrants of the enclosure, thereby promoting more complete engagement with the environment (Barros et al., 2024). Future studies might extend this approach to pelagic and demersal species to explore how enrichment design interacts with spatial ecology and swimming behaviour.
The results of this study reinforce the need to move beyond generic enrichments and adopt evidence-based strategies that reflect the species’ ethological and cognitive needs. By extension, these principles are broadly relevant for elasmobranch husbandry and welfare research. The demonstration that foraging challenges can stimulate natural and complex behaviours in Potamotrygon stingrays has significant implications for ex situ conservation. Aquariums and zoological institutions play a vital role in the conservation of threatened species, such as many elasmobranchs (Conway, 2011; Da Silva et al., 2019; Dulvy et al., 2014). By enhancing animal welfare through adequate and effective enrichments, these institutions not only improve the quality of life of individuals under their care but also contribute to successful breeding programs (Carlstead and Shepherdson, 1994; Colbachini et al., 2021). The display of natural behaviours, such as those stimulated in this study, can also increase public engagement and conservation awareness, as suggested by Smith et al. (2025).
In conclusion, the feeding enrichment strategies applied in the present study were effective in stimulating foraging behaviours and reducing inactivity in captive Potamotrygon stingrays, with significant variations depending on the difficulty level of food access. The observation of species-typical behaviours, the demonstration of effort to obtain food, and the individual variability in responses highlight the complexity of these animals’ welfare. These findings provide a foundation for applying similar enrichment approaches across other elasmobranch taxa, adapting them to species-specific ecologies and cognitive capacities. Future research could explore the relationship between enrichment and neuroplasticity, as suggested by Salvanes et al. (2013), and investigate whether long-term exposure to different types of enrichment affects physiological and reproductive health, as indicated by Colbachini et al. (2021) regarding olfactory enrichment. The continuous optimisation of enrichment practices, tailored to individual and species-specific needs, is fundamental to promoting the welfare and success of conservation programs for these fascinating freshwater elasmobranchs.
Data availability statement
The datasets presented in this study can be found in online repositories. The names of the repository/repositories and accession number(s) can be found below: The datasets analysed for this study can be found in the Mendeley Data Repository: Gonzaga, Cassia; Azevedo, Cristiano; Colbachini, Helen; Reisfeld, Laura; Padilha, Fabiana; Gutierrez, Rafael; Pizzutto, Cristiane (2025), “Behavioural assessment of Potamotrygon stingrays under different food enrichment strategies”, Mendeley Data, V1, doi: 10.17632/8t744kp5p5.1.
Ethics statement
The animal study was approved by Ethic Committee on Animals Use of the School of Veterinary Medicine and Animal Science of the University of São Paulo (CEUA/FMVZ) under protocol number 2179230320. The study was conducted in accordance with the local legislation and institutional requirements.
Author contributions
CG: Conceptualization, Writing – review & editing, Methodology, Writing – original draft, Data curation, Investigation, Visualization, Validation. CA: Writing – original draft, Formal Analysis, Visualization, Writing – review & editing. HC: Formal Analysis, Writing – original draft, Methodology, Data curation, Visualization, Conceptualization, Writing – review & editing. LR: Writing – original draft, Visualization, Conceptualization, Supervision, Methodology, Writing – review & editing. FP: Methodology, Writing – original draft, Visualization, Investigation, Writing – review & editing. RG: Methodology, Writing – review & editing, Conceptualization, Writing – original draft, Investigation, Visualization. CP: Project administration, Validation, Methodology, Supervision, Conceptualization, Visualization, Writing – review & editing, Writing – original draft.
Funding
The author(s) declared that financial support was not received for this work and/or its publication.
Acknowledgments
The authors would like to thank the entire team at the São Paulo Aquarium for allowing the study to be conducted and for their assistance in creating the environmental enrichment items.
Conflict of interest
Authors HC, LR, FP and RG were employed by Aquário de São Paulo.
The remaining author(s) declared that this work was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.
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Keywords: animal welfare, aquarium, environmental enrichment, foraging behaviour, Potamotrygon
Citation: Gonzaga CRR, de Azevedo CS, Colbachini H, Reisfeld LC, Padilha FLA, Gutierrez RC and Pizzutto CS (2026) Behavioural assessment of Potamotrygon stingrays under different food enrichment strategies. Front. Ethol. 4:1752180. doi: 10.3389/fetho.2025.1752180
Received: 22 November 2025; Accepted: 29 December 2025; Revised: 22 December 2025;
Published: 21 January 2026.
Edited by:
Paul Rose, University of Exeter, United KingdomReviewed by:
Scott Nunes, University of San Francisco, United StatesDanielle Free, Marwell Zoo, United Kingdom
Copyright © 2026 Gonzaga, de Azevedo, Colbachini, Reisfeld, Padilha, Gutierrez and Pizzutto. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner(s) are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.
*Correspondence: Cristiano Schetini de Azevedo, Y3Jpc3RpYW5vLmF6ZXZlZG9AdWZvcC5lZHUuYnI=