Bioremediation is a well-documented option that involves applying microorganisms to neutralize petroleum in the environment [13]. It targets those microbes capable of synthesizing enzymes that cleave C:H bounds from petroleum hydrocarbons and transforms them into harmless and less persistent molecules [14]. However, while the microbial biodegradation of hydrocarbons and crude oils has been widely studied for decades, most studies have focused on light crude oils and their low molecular weight fractions or purified components [15]. In contrast, the microbial biodegradation of HCO and EHCO, particularly by fungi, has been scarcely studied. Only a few fungal strains isolated from extreme environments are able to degrade asphaltenes and high molecular weight PAHs [16]. _Aspergillus fischeri_ (previously _Neosartorya fischeri_), isolated from an asphalt lake in Venezuela, was the first microorganism able to grow using purified asphaltenes as the sole carbon source [17]. This fungus set a unique precedent demonstrating its remarkable ability to degrade extremely complex hydrocarbon molecules, especially high molecular weight PHAs [18]. The extremophilic fungus _Pestalotiopsis palmarum_ BM-04 isolated from an asphalt lake in Venezuela synthesizes oxidative exoenzymes that catalyze the biotransformation of maltenes, asphaltenes, and the petroporphyrins-rich fraction of biotreated EHCO [19]. _Paecilomyces variotii_, _Fusarium decencellulare_, _Candida palmiocephalia_, and _Pichia guilliermondii_, isolated from a petroleum activity site in Indonesia, were able to degrade 10-15% of resins and asphaltenes using BAL150 light crude oil as the sole carbon source [20]. A chloroperoxidase obtained from _Caldaromyces fumago_ transformed the porphyrin-free asphaltene fraction recovered from Maya HCO, reducing it by 24% [21]. Furthermore, _Daedaleopsis_ sp., isolated from a forest in Iran, showed biodegradation of 38% of the asphaltene and aromatic fractions of HCO [22]. The Gulf of Mexico (GoM) is rich in petroleum reservoirs, and since 2017, their ultra-deep waters have been exploited to obtain crude oil [23]. Therefore, it represents an ideal prospecting source to isolate indigenous fungal strains adapted to deep-sea conditions and capable of degrading crude oil. In a previous study, the fungal taxa _Aurebosidium_ sp., _Penicillium_ _pencilium_ sp., _Philaccephalia_ sp., and _Cladosporium_ sp. isolated from sediments of the Mexican economic exclusive zone (EEZ) of the GoM were identified as able to metabolize alkane and alkene, long-chain hydrocarbons poorly degraded by bacteria, as the sole carbon sources [24]. Furthermore, the RNA-seq expression analysis of _Penicillium_ sp. cultured with hexadecane or 1-hexadecene showed the upregulation of genes involved in transmembrane transport, metabolism of six-carbon carbohydrates, and nitric oxide pathways [24]. In this study, we set out to identify culturable strains of marine fungi native to the seafloor of the Mexican EEZ of the GoM with the ability to degrade untreated EHCO. _Alternaria_ sp. was the only isolate identified as capable of growing using EHCO as the sole carbon source and degrading a significant portion of the whole EHCO.