When I had my DP, I fed her raw shrimp. These shrimps were frozen at the grocery store, but I thawed in a cup of aquarium water. It didn't dirty the water because I held the shrimp by the tail and dip it in the water. My DP would eat until her tummy is slightly rounded, then I remove. If not raw shrimp, then I fed live worms because worms are usually packed full of vitamins. These become a lot more messy during feeding. Get a turkey baster and suck up all remaining pieces of the worm.
Most sources feed frozen blood worms and snails. Snails are nutritious, and blood worms are better off being treats for DP. I didn't go this route because blood worms are expensive and I didn't want to keep a separate snail tank. I only fed snails if my LFS had some to give away.
1 piece of raw shrimp can be cut up into smaller pieces and it can last over one week of feeding. Its a good idea to thaw these raw shrimp in vitamin water, such as vitachem. Vitachem is good cheap insurance for your DP to get all of its vitamins because these fish can live past 5 years if you keep them well fed (but never overfed) and at least 50% weekly water changes.