The tectonically active landscapes of Darjeeling-Sikkim Himalayan (DSH) are under the threat of great earthquake, MW > 8.0 (a seismic gap of over 200 years), and the MFT or MBT is prone to rupture above 8 m. Due to the dynamics of bedrock fluvial system, the geo-tectonic analysis of fluvial network is fundamental to understanding topographical evolution by gradually incising mountain surfaces and preserving markers of landscape adaptation in the DSH orogens. Here, the application of tectonic geomorphology using MATLAB-based TopoToolbox 2 functions (viz., stream power incision model, stream length-gradient index, hypsometric integral, chi plot and knickpoint finder) reveals that the fluvial anomalies and geomorphic markers contain unique information about the active tectonic regime, dictating (1) deviation of equilibrium channel form, (2) sensitivity of equilibrium channel gradient to uplift rate and (3) equilibrium fluvial relief in active collision zone. Normalized channel steepness index, drainage density, stream length-gradient index, hypsometric integral and relative relief are identified as the most dominant and highly effective variables to elucidate the fluvial response to tectonic perturbation along the drainage system of Tista River basin.