Amount of vegetation

20 gal tank with tetras, 2 black molly's, one orange molly, clown loaches,
few others and a large pleco.

I have 4 or 5 medium sized shells in there, one is used as a home by the
pleco.

I have one live plant which grows pretty wildly (long). I cant remember what
it is its been so long since i bought it. I have one artificial weed patch
(That flat thing they say is for fry to hide in).

I did have one longer plastic plant but took it out because it seemed to be
taking up too much room and the fish seemed like they were avoiding it and
tryting to swim around it.

How much vegetation should I have..generally? And what about shells and
places for fish to hide, etc.

Is it a bad idea to change the environment slightly to increase the area the
fish have to swim and move around?


TIA
Jeff