Coexistence of Native and Alien Fish: Food Overlap and Feeding Strategies of Pseudosphromenus dayi (Köhler, 1908) and Trichopodus trichopterus (Pallas, 1770) in a Tropical Coastal Wetland, India

Understanding the dynamics between native and invasive species in aquatic ecosystems is crucial for effective conservation and management. This study investigates the diet composition and niche overlap of the native paradise fish (Pseudosphromenus dayi) and the introduced three-spot gourami (Trichopodus trichopterus) in a coastal wetland in Kerala, India. Through a comprehensive diet analysis, the study aims to reveal trophic dynamics and potential competition between these coexisting species. A substantial diet overlap of 0.73 indicates significant resource sharing, particularly in detritus, plant matter, Chlorophyta, insect remains, Cyanophyta, and Crustacea, highlighting a pronounced interaction between the paradise fish and three-spot gourami. Abundant resources in the wetland likely alleviate interspecific competition, facilitating the coexistence of both species. The presence of microplastics in the gut of both species signals increased human intervention and plastic pollution in the watershed and wetland. These findings underscore the importance of considering dietary preferences and ecological behaviours in assessing interactions between native and invasive species. Effective management strategies are crucial to mitigate potential competition and maintain the ecological integrity of wetland habitats. Continuous monitoring of invasive freshwater fishes is recommended for early detection and the implementation of management plans to address potential threats.