Where do settings normally go? about bass HOT 1 CLOSED

Correct. That will cause nvm use iojs to be executed at the startup of every fish session. Alternatively, you could define this function:

function nvm
    bass source ~/.nvm/nvm.sh ';' nvm $argv
end

and save it as ~/.config/fish/functions/nvm.sh. Then you can use the nvm command as if you were in bash. For example:

nvm ls-remote

would invoke ls-remote to list all remote versions, and

nvm use v0.10.36

would activate version 0.10.36 of nodejs (if it is installed).

from bass.