I have purchased fish from dallas north aquarium, Frank's tanks and Midcities aquarium. Also Apex Aquariums but not sure if they are there anymore.
Pretty much every store is going to need the fish treated for flukes and ich. I prefer Franks tanks, he runs many fish through prazi and runs copper in the fish systems. Has some nice frags too.
DNA you can usually see some fish with illness somewhere in the store, they had several batches of flasher wrasses over the spring so I picked up a couple and they ordered a molly Miller blenny for me. A yellowfin flasher is in my display a few months now.
The blenny and a mccoskers wrasse are in quarantine. The wrasse broke with ich and developed a bacterial infection. I have gotten those resolved and am just in an observation period before moving them to the display.
Been a while since I purchased from The other 2 stores.
Definitely plan to quarantine, Frank's does the most treatment I am aware of and hes an awesome guy (whys he gotta be way in southwest FW!)
If you have not already, check out the LFS map at dfwmas.org.