ABSTRACT Gourami fishes of the genus Trichogaster are widely distributed across South and Southeast Asia but pose taxonomic challenges due to strong morphological similarity. This study applied an integrative landmark-based morphometric framework combining the Truss Network System (TNS) and Geometric Morphometrics (GM) to quantify interspecific phenotypic variation among T. fasciata , T. lalius , and T. chuna . Truss distances were size-adjusted to remove allometric effects, while GM analyses were conducted following Generalised Procrustes Analysis to isolate shape variation independent of size, position, and orientation. Multivariate analyses, including discriminant function analysis (DFA) for TNS and canonical variate analysis (CVA) for GM, revealed statistically significant phenotypic differentiation among species. TNS-based DFA showed overlap between T. fasciata and T. chuna but clear separation of T. lalius , primarily driven by differences in head morphology and caudal peduncle structure. GM-based CVA further resolved all three species, highlighting shape variation associated with the head region and body depth profile. Contrary to earlier assessments that synonymized T. lalius with T. fasciata , the present findings support its recognition as a valid species. Overall, the combined use of TNS and GM offers a robust approach for resolving taxonomic ambiguity in morphologically similar gourami species, with implications for biodiversity assessment and conservation planning.
De et al. (Mon,) studied this question.