Zucchini or spirulina flake will usually do the trick.
Also, some species of plecos are carnivores 
While at Stevens last week, I told him about losing a fish, he asked what I was feeding them, I said pellets (Plecocaine # 3 and # 4). He said that he only feeds his fish flakes, including spirulina.. I do have some flakes I got from Wet Thumb so I have been feeding them that lately and doing the pellets sporadically for a treat...
QUESTION: are you supposed to soak the pellets before feeding them to the fish ?
I did a TON a researching if you remember about a year ago when I was having troubles. I feed spirulina and NLS pellets. The flake is just a good food. But, as my fish continue to grow... dang, they need a LOT of flake food.
So, I start with flake food and then put in some NLS. I tested the foods I had around the house by soaking them in water... the NLS was the only one that hardly swelled up at all. This is why I stick with it.
I feed the 1mm pellets to all the tanks, except the one with the larger fish in it. That I use the 2mm pellets. Just recently started adding the Medium Fish size pellets (I forgot the size).
Knowing how much you feed your fish... test whatever pellets you are using and see if they swell in water.