Welcome to mfk. Glad to see you’re being proactive about your fish! Recently, my Tat has just begun eating pellets. Here’s some info I offered to another member here, hopefully it can help you as well.
Breaking an armatus off of live is definitely challenging. Payara aren’t like most fish where they’ll eat before they starve themselves to death. They have absolutely no problem dying for their preferred food convictions. One good piece of advice I’ve tried is to take a fish hook and cut it to about 1/4” below the eyelet, then tie the hook to a very fine piece of monofilament and pierce a piece of shrimp onto it. Then during feedings jerk it around a bit to simulate a living bit. This will act as a good middle ground to help them adjust and consider the market shrimp “food”. I had the luxury of bass that will hit anything I throw into the tank as well. If you have other fish already on market shrimp it will significantly help. But just remember, from what I’ve seen, when it comes to payara take it safe and slow. Feed him live every few days if he isn’t eating what you’re throwing in. Payara already have a tough time adjusting to aquaria And you’re basically trying to rewrite its basic instincts so don’t make them hate life. If you’re patient I’m sure he’ll adjust. Also just want to say I’m in no way a Payara expert these are just the methods that helped me and hopefully they can help you
