Exotic fish Cyprinus carpio can occupy a separate niche, when introduced among indigenous fishes may possesses threat to small fishes.

ABSTRACT Ecomorphology is the study of the interaction between an organism's morphology and its surroundings. An interesting field of research that can combine the relationship between fish morphology and their environment is the ecomorphology of freshwater fishes in India. This study examined the morphometry and meristic traits of five native freshwater fishes that were analysed by UPGMA method to understand their adaptive radiative capacity and the basis of clustering of characters. Common carp (Cyprinus carpio), Mrigala (Cirrhinus mrigela), Bele (Glossogobius guiris), Punti (Puntius sophore) and Moya (Amblypharyngodon mola) species were used for the study. Results of adaptive radiation analysis showed being a bottom feeder, Cirrihinus mrigala occupy a completely separate cohort. Glossogobius giuris is bottom dweller predator, feeds on small fish, in this combination Puntius is the closest prey. They also compete for same niche. The Cyprinus may affect, mainly the Amblypharyngodon mola. They can compete for food and share same niche. As, all of them are opportunistic omnivore, variation in “gut length” is not significant. The weightage of characters analysis presented total length is an important character, because mature fish length is highly variable. Head length and eye diameter plays an important role in adaptation. This study may serve to understand the competition model. When we plan to release an “exotic species” for economic importance, possible ecological effect can be assessed from this kind of competition model studies in various combination of species in the aquatic ecosystems. Such ecomorphology studies has pivotal role in gathering information of adaptive radiative features of a variety of fishes, which might help in development of conservation efforts, sustainable aquaculture practices and fisheries management in near future. Key Words: Adaptive radiation, UPGMA, meristic and morphometric measurements, Character weightage, competition model.