Hi and welcome to the forum
I used to wander around the bush and follow water ways from one end to the other for my ideas about aquascaping. Unfortunately most people cant do that, and even I don't do it up north due to water lizards, aka chocodiles.
Most fast flowing waterways consist of sand, mud and gravel with a few rocks and sunken branches or trees/ tree roots. You might get grasses and a few other plants growing along the edge of the bank.
Calmer pools or ponds are where the plants grow. Depending on which country the fish come from, they will have different plants growing in the pools. Most pools have sand on the bottom and this usually gets covered in mud/ silt. The plants completely fill up these pools and it can be difficult walking through them due to the plants wrapping around your legs. The pools can be anywhere from 1ft to 6ft or more deep and the plants regularly grow to 3 or more feet high.
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There was a Japanese guy "Takashi Amano" you did lots of biotopes. He also did a couple of books. If you google him, there are lots of images of his work.
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You don't need this info now, but the following link has information about what to do if your fish gets sick. It's long and boring but worth knowing. It's worth a read when you have some spare time.
https://www.fishforums.net/threads/what-to-do-if-your-fish-gets-sick.450268/
