Install QGIS

Ubuntu

sudo sh -c 'echo "deb http://qgis.org/debian xenial main" >> /etc/apt/sources.list'

sudo sh -c 'echo "deb-src http://qgis.org/debian xenial main " >> /etc/apt/sources.list'

wget -O - http://qgis.org/downloads/qgis-2017.gpg.key | gpg --import

gpg --fingerprint CAEB3DC3BDF7FB45

gpg --export --armor CAEB3DC3BDF7FB45 | sudo apt-key add -

sudo apt-get update && sudo apt-get install qgis python-qgis

Click on the elephant on the left

Under connections press New

Add a name (actually important)

Add the correct host and port and set the name of the database

Test the connection and press OK

Then connect, login and select the table you want and add.