The Biobrio 12(3&4), 2025

Morphology and ontogenetic development of the olfactory organ in Colisa fasciatus from freshwater habitats of Gaya, Bihar

Ashish Kumar

ABSTRACT:

The present study investigates the morphological organization of the olfactory organ in Colisa fasciatus (barred gourami) collected from freshwater habitats of Gaya district, Bihar. Detailed anatomical dissection and microscopic examination revealed that the olfactory apparatus comprises an elliptical olfactory rosette with radially arranged lamellae lined by sensory epithelium. The number of lamellae ranged from 15 to 45 and exhibited a strong positive correlation with body length (r = 0.93, p < 0.05), indicating ontogenetic expansion of the sensory surface. A well-developed accessory olfactory sac and distinct vase-shaped olfactory bulbs connected to paired olfactory tracts were also observed. These findings suggest a highly specialized chemosensory system adapted to the ecological conditions of the species' habitat. The study provides baseline morphological data relevant to comparative anatomy, sensory ecology, and environmental assessment.

Keywords:    

Colisa fasciatus, olfactory organ, olfactory lamellae, chemoreception

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