  Evidence of nematic effects in the mixed superconducting phase of slightly
underdoped $\text{Ba}(\text{Fe}_{1-x}\text{Co}_x)_2\text{As}_2$ is reported. We
have found strong in-plane resistivity anisotropy for crystals in different
strain conditions. For these compositions, there is no magnetic long range
order, so the description may be ascribed to the interplay between the
superconducting and nematic order parameters. A piezoelectric-based apparatus
is used to apply tensile or compressive strain to tune nematic domain
orientation in order to examine intrinsic nematicity. Measurements are done
under a rotating magnetic field and the analysis of the angular dependence of
physical quantities identifies the cases in which the sample is {\em
detwinned}. Furthermore, the angular dependence of the data allows us to
evaluate the effects of nematicity on the in-plane superconductor stiffness.
Our results show that although nematicity contributes in a decisive way in the
conduction properties, its contributions to the anisotropy properties of the
stiffness of the superconducting order parameter is not as significant in these
samples.
