A comparison of fish diversity was carried out among 45 sites within four localities in the Mexican Tropical Western Atlantic (TWA) and Tropical Eastern Pacific (TEP) regions. Several taxonomical and functional diversity indices were considered, and their relationships with the coral cover were investigated in each locality. We found that despite a lower number of species, the localities within the Mexican TEP region had equal or even higher functional diversity than the localities in the Mexican TWA region where sites within the Caribbean Sea appeared particularly poorly diversified. Divergent relationships between fish diversity and coral cover were observed between the two oceanic regions. On the one hand, it tended to be positive in the TWA, and on the other hand, it was negative in the two TEP localities. This contrast may be explained by the low coral species richness and the homogeneous habitat (low structural complexity) provided by a high cover of coral in the TEP. This study highlighted how the fish assemblages can be functionally diversified within the TEP, a region generally considered poorly diversified, and how the relationship between fish diversity and coral cover may vary between oceanic regions.

在墨西哥热带西大西洋（TWA）和热带东太平洋（TEP）地区四个地方的45个地点之间对鱼类多样性进行了比较。考虑了几个分类学和功能多样性指数，并在每个地方调查了它们与珊瑚覆盖的关系。我们发现，尽管物种数量较少，但墨西哥TEP地区内的地区具有比墨西哥TWA地区内的地区相同或更高的功能多样性，在墨西哥TWA地区，加勒比海地区的地区尤其多样化。在两个海洋区域之间观察到鱼类多样性与珊瑚覆盖之间的不同关系。一方面，它在TWA中倾向于为阳性，另一方面，在两个TEP地区中则为阴性。这种对比可能是由于TEP中珊瑚覆盖率高而提供的珊瑚物种丰富度低和栖息地均一（结构复杂性低）所致。这项研究着重介绍了在TEP中如何将鱼类组合在功能上进行多样化（该地区通常被认为是多样性较差的地区），以及在海洋区域之间鱼类多样性与珊瑚覆盖之间的关系如何变化。