TBH the discus are justs as likely to eat Cardinals as Angels are, if anything, my Discus were far more predatory than the angels (which were just gnarly tempered but ok in their the tank i had).
You DEFFINATELY dont want Silver Dollars
tbh they are one of those fish along with the silver sharks that i would love to see less of in the shops because people just dont appreciate how big they get, how much space they use aand quite how quickly they can eat plants!!
Why is your PH so low? What is your GH and KH? Im assuming you use tapwater? What are your other parameters? (amonia, nitrite, nitrate). Discus are fussy, still cichlids and fussy with tankmates andvery fussy with water parameters. Probably ok for your tank but people underestimate discus. They are cichlids and still aggressive.
Pearl Gouramis and Moonlight Gouramis are great
Beautiful fish,less aggressive then the Opalines and Golds, less prone to illness and death like the Dwarf Gouramis and bigger than the Honey Gouramis.
Also the Hatchet Fish (the Silvers are larger than the Marbled) are great surface dwellers without being predatory like Panchax and butterfly fish.
/www.planetcatfish.com/catelog/species.php?species_id=327
