Which walmart did you say this was..cas I'd like to call them and inquire how they obtained "wild" bettas..AND have sale staff that are experienced enough to know that they are "wilds" and that they need a heavily planted 10 gallon to themselves.
I haven't ever seen a "fish sale" at Walmart either..and I am a REGULAR Walmart customer..some of the stores in my area know me by name during certain shifts...I'm like clockwork lol. And if this one is having fish sales..I want to know about it..so I can inquire at mine why they don't ever. Cas I see the same sad faces sitting in those cups everytime I go.
I'd be very interested to know what you feed your Moorish Idols as well, if you don't mind, and how you acclimated them upon their arrival at your home, how many you have, and what size tank they reside in. Thsoe are just amazing fish!