Silver dollar breeding and plants

[TheLastGreen]

Does anyone have silver dollars? These buggers are ferocious plant eaters, they apparently don't eat duckweed (but they did anyway). I'd like to breed them and get some plants for them that they won't eat, any advice?
Tank set up
Temp: 26C
Inhabitants:
5 (small) silver dollars
3 large silver dollars
1 Angel fish
1 Betta fish
1 Molly
1 Plecostomus
1 zebra nerite snail
Size: 100l or about 27gal
(I have a feeling the tank is getting way too small or is too small already)

 

[Okapizebra]

I don't know anything about breeding silver dollars, but the tank is definitely too small. I would go 55+ gallons. I've heard anubias and Java ferns tasted bad to fish so that could be worth a try but I wouldn't be surprised if they devour any live plant you try.