I have just created a new env with python 3.5 using anaconda (called it python35). My root env points to python 2.7.11. I cant seem to launch ipython with this new env, here is
AFAIK, different environments in anaconda (and in venv as well) are activated by prepending env path to $PATH environment variable. It means, that if some file (eg, ipython) is not found in env path (the first entry of $PATH), the system searches for it in consequent entries of $PATH and finds it in root environment (that stays in $PATH). To fix the behavior, you need to install its own copy of ipython to anaconda env:
source activate python35 (or simply activate python35, depending on the OS)conda install ipython-notebook