This work aimed at morphologically identifying nematodes isolated from individuals of Parassi mullet (Mugil incilis) captured in the Cartagena bay and to establish their intensity and prevalence on the rainy season. For that purpose, 378 individuals of Parassi mullet were collected at three sites in the bay between June and November 2009. Then, the collected individuals were taken to the laboratory for dissection and analysis of their visceral cavity. Nematodes isolated from each individual were counted and preserved in 10% formalin, then fixed and clarified. The identification was carried out by optic microscopy and was based on the following morphological characteristics: position of the excretory pore, tail shape, length and shape of the ventricle, and presence, length and position of the anterior and posterior intestinal caecum and of the ventricular appendix. Before clearance, a histological section was performed to observe the shape of the intestinal tract. Nematode parasites belonging to the genera Pseudoterranova and Contracaecum, larval III stage, were found. Based on the entire sample of fish, parasite prevalence was estimated to e between 80% and 100%, while parasitic intensity ranged between 4 and 23 parasites per fish.