Discus in a 125

Hey, would black skirt tetra work with Discus? Or is it that Cardinals may do ok in the warmer water..?
 
125 gals is a great tank to get started with discus.
I would suggest you get it all set up, planted and cycled first, and begin introducing whatever dither fish you want to keep. A nice school of various Cories should likely be first, then some RummyNoses if you like them, followed by the cardinals if those are your choices. Get it up & running, settled in well with good params, and plants showing some growth, then add your discus. (Around 7-10 weeks later.)
Again my suggestion would be to get al least 3" specimens, preferably 4" - single strain, or mixed strains - whatever coloration combo you like - but most important, get them from an experienced, reliable source that is well known to provide healthy, well-shaped fish - and get them all from the same source, together, not in batches, even though you'll be adding a heavy bio-load right off the bat- usually safer that way than trying to add other new discus at later periods, especially if from different sources.
Your tank could easily handle 12 or so discus, but it would be safer and less complicated as time evolves, to go with 8 or 10.
It may help you to have a read first, of my illustrated Guide to Getting Started with Discus - in the simplydiscus.com form - here's the direct link:

www.forum.simplydiscus.com/showthread.php?86009-Beginner-s-Guide-to-Getting-Started-with-Discus

Also, just for you to have a peek, so that it may help you decide, here's 2 sets of pics of my planted discus tank:
First set of pics is several months ago when I had a single strain of Red Snake Skins, and then recently as the plantings matured, and I changed up some of the discus.

http://s1105.photobucket.com/albums/h357/discuspaul/FTS-Osaka260
http://s1105.photobucket.com/albums/h357/discuspaul/2tanks.

Hope this helps you to get thinking and started.
Don't hesitate to PM me anytime if I can be of any further help.
Best of luck.
 
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