Hey, im pretty new to the hobby i've had an aquarium for about 1.5 year but never really done any research only done as the one i bought the aquarium told me.
I would want something diffrent then my tetras something that lives at the middle/bottom of the aquarium that fits well with my south american neon and kardinals, just learned i had kardinals aswell the old owner of this tank said there were only neon tetras in the tank and the small ancistrus i believe he said. This weird but awsome fish had to move though he kept tearing my plants from the sand. was plastic plants before i got the tank but i didn't like the plastic look on them so i got some real plants.
If there are any other fish thats not tetras that comes from south America that would fit in the aquarium i got i would love to hear some information about them, like species if there are a certain groups of fish i could get, also how many i should get
I don't want to get any fish from another continent since i feel like mixing fish that don't live in the same water as one and other is not kind.

I also have a question about my neon and kardnials they seems like they fight a lot, do i have to many of them so i should remove?

The aquarium is a 100 liter (29 gallon) thats heavy planted with lot's of driftwood and a Ph at around 6.2

I was also told that the price of the aquarium was so high since it came with a top notch filter for the tank says Fluval 205 on the filter was i just cheated on the tank or is this a top notch filter for the aquarium?