The African catfish Clarias gariepinus is a freshwater species native to nearly all of Africa and a small part of Asia. Due to being a generalist species, highly fertile and able to survive in a wide range of environmental conditions, the African catfish has become invasive in many non-native systems where it was introduced, bringing negative impacts to wild ecosystems. In Brazil, C. gariepinus was introduced from Africa for aquaculture in 1986 and established itself in the wild within a decade, after escaping from aquaculture ponds and being further translocated to be used in recreational fishing. As further evidence of the expansion of this invasive species in Brazil, we sequenced the mitochondrial control region and cytochrome b markers to confirm the occurrence of C. gariepinus in a major river in a protected area in the southeastern region, and to assess its genetic diversity. Morphometric data was also collected to aid species identification and to compare to other invasive populations in Brazil. The analysis of 24 specimens revealed a single haplotype for each marker. The single cytochrome b haplotype is identical to a haplotype from the Democratic Republic of the Congo, unveiling the possible genetic origin of the C. gariepinus lineage that invaded Brazil. Morphometric data suggests consistency in the morphometric traits of C. gariepinus invasive populations in Brazil. The assessment and monitoring of the distribution of C. gariepinus in non-native areas are crucial for the maintenance of native freshwater biodiversity and ecosystem functioning worldwide.

非洲鲶鱼Clarias gariepinus是一种淡水物种，原产于几乎整个非洲和亚洲的一小部分地区。由于非洲鲶鱼是一种多面性物种，繁殖能力强，能够在广泛的环境条件下生存，因此非洲鲶鱼已成为其引入地区的许多非本地系统的入侵者，给野生生态系统带来负面影响。在巴西，C. gariepinus于 1986 年从非洲引入用于水产养殖，并在从水产养殖池塘逃逸并进一步转移用于休闲捕鱼后，在十年内在野外扎根。作为这种入侵物种在巴西扩张的进一步证据，我们对线粒体控制区和细胞色素 b 标记进行了测序，以确认C. gariepinus在东南部地区保护区的一条主要河流中的存在，并评估其遗传多样性。还收集了形态测量数据，以帮助物种识别并与巴西的其他入侵种群进行比较。对 24 个样本的分析揭示了每个标记的单一单倍型。单个细胞色素 b 单倍型与来自刚果民主共和国的单倍型相同，揭示了入侵巴西的C. gariepinus谱系的可能遗传起源。形态测量数据表明巴西C. gariepinus入侵种群的形态特征具有一致性。评估和监测C. gariepinus在非本地地区的分布对于维持全球本地淡水生物多样性和生态系统功能至关重要。