The Mexican cavefish, Astyanax mexicanus (Characidae), has become an important model in evolutionary physiology and developmental biology, providing insights into the evolution of sensory systems, pigmentation, and metabolism. In contrast, comparatively little is known about the natural history and trophic ecology of this elusive cave inhabitant. We investigated cavefish from three independently colonized cave systems (Pachón, Tinaja, and Sabinos), which are located in the Sierra de El Abra of northeastern Mexico. Samples were collected multiple times throughout the year to investigate variation in body size, sex ratios, proportions of individuals with empty guts, and diet composition. We found consistent differences in body size among caves, and sex ratios were generally female biased, although to varying degrees. Gut content analyses indicated that cavefish consume food throughout the year, and diets are dominated by detritus, plant materials, and aquatic invertebrates. Especially in the Pachón cave, where we had the densest sampling, there was evidence for seasonal changes in diet composition that coincided with the rainy and dry seasons. Our findings potentially suggest that the cave environments in this system are characterized by continual nutrient limitation, rather than intermittent periods of starvation.

墨西哥洞穴鱼Astyanax mexicanus（Characidae），已成为进化生理学和发育生物学的重要模型，提供了对感觉系统、色素沉着和新陈代谢进化的见解。相比之下，人们对这个难以捉摸的洞穴居民的自然历史和营养生态知之甚少。我们调查了来自三个独立殖民的洞穴系统（Pachón、Tinaja 和 Sabinos）的洞穴鱼，这些洞穴系统位于墨西哥东北部的 Sierra de El Abra。全年多次收集样本，以研究体型、性别比例、空肠个体比例和饮食组成的变化。我们发现洞穴之间的体型存在一致的差异，性别比例普遍偏向女性，尽管程度不同。肠道含量分析表明，洞穴鱼全年都在消耗食物，饮食以碎屑、植物材料和水生无脊椎动物为主。尤其是在我们采样最密集的 Pachón 洞穴中，有证据表明，与雨季和旱季相吻合的饮食成分季节性变化。我们的研究结果可能表明，该系统中的洞穴环境的特点是持续的营养限制，而不是间歇性的饥饿。