First report of odontoma in Petroscirtes breviceps (Valenciennes, 1836) from Rameswaram Island, India.

Odontogenic tumours are rarely reported in teleost fishes, and detailed histopathological descriptions of these lesions remain limited. This study describes a rare case of compound odontoma in the striped poison-fang blenny mimic, Petroscirtes breviceps (Valenciennes, 1836). Among 30 examined individuals, one male specimen measuring 13 cm in total length and weighing 12 g presented with a distinct tumour-like growth in the oral cavity. Gross examination revealed a localized, pale pink, fleshy odontogenic lesion attached to the left side of the lower jaw. The mass contained numerous toothlet-like structures of varying sizes, suggesting progressive tumour-associated odontogenic differentiation. Histopathological analysis showed a well-circumscribed, non-invasive mass composed of multiple irregular denticle-like structures embedded within a moderately cellular fibrovascular stroma. These denticles exhibited features consistent with dental tissue organisation, including eosinophilic dentine-like mineralised matrices surrounding central pulp-like cores, with enamel-like caps observed in some areas. The lesion also contained proliferating fibroblasts, mesenchymal cells resembling dental papilla, and scattered nests of odontogenic epithelium. No evidence of cytological atypia, necrosis, vascular invasion, inflammatory infiltration, or significant mitotic activity was observed, confirming the benign nature of the tumour. The presence of well-differentiated tooth-like structures composed of dentine-, cementum-, and enamel-like materials supported a definitive diagnosis of compound odontoma. To the best of our knowledge, this represents the first documented report of odontoma in P. breviceps from Rameswaram Island, India.