As I stated somewhere else, buying fish is like buying curtains, one person likes light-brown ones, another white with big flowers, another yellow ones, and someone else will just stick black bin-liners across the window to keep the sun out...
With pictus cats, you need to avoid small fish, as they will be seen as a food-source by the Pictus.
Day-active fish could be just about anything except for most catfish, so that's pretty easy to just go to the local shop and look at what you like, and choose something that is suitably large (NOT neons or cardinald). I'm quite fond of rainbow fish, but there are larger tetras, barbs, danios, gouramis, smallish cichlids (Angels, Ram's, Apisto's, etc) that are nice too. It's all a question of what you like. Obviously, larger live-bearers, like Molly's or Platies would work too, just don't expect to ever see any babies... [That could be a good thing, as I'm currently trying to find somewhere to home my 30-40 molly fry...]
You probably want to get a single Ancistrus to keep the algae at bay.
Plants: Vallisneria species are easy to care for, and Java Fern/Moss are both relatively easy, as well as several other type of plants. If you buy a selection of 3-4 that are "easy", then I'm sure at least one or two will take off like there's no tomorrow.

[I had a bucket full of Vallisneria from my inherited 40g tank, I put some in my big tank and chucked the rest in the bin. It just grows and grows.]
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Mats