Take it off Auto and set it to P for now. The auto setting gives you no control over ISO and it could be using a high one giving you crappy pics. Use the Func button to set an ISO of 100. You can't select an ISO on Auto. Within the same menu scroll down to the bottom 2 icons and select picture quality Superfine and L.
Off the top of my head I think the night setting combines a long-ish exposure (say 1 sec) with flash to give you a mix of ambient light (i.e. dark) and flash. I'm not sure if this is the best setting for, at a guess, somebody holding a fish at night. Maybe just the normal P setting with flash on. try it and see. Or maybe the Portrait setting. In the main menu make sure the autofocus assist beam is on. Even then it may struggle to focus in the dark and you may have to resort to using the manual focus while guessing the distance. This is a basic improvement provided by the camera. The rest unfortunately comes with practice and experience.
I've had a G5 for something like 5 years but I retired it some time ago. It has provided some top class pics that I've on occasion confused with having been taken by the Canon 10D dslr that I also had at the time. But it has also supplied me with plenty of dogs. Noisy due to high ISO (which is only 400 with this camera), and poorly focused. Within its limitations, it's a good camera and ideal to learn with, having all the manual controls too. And in case you're thinking about it, buying a newer camera won't necessarily give you better pictures.
