Just on a side note, pellets, wafers, and even flake food can become "stale". If you've kept your food for some time or even if its just been sitting on your LFS shelf for a few years it'll take a long time to soften when placed in water. I doubt places like Petco/smart use their staff to frequently check dates either. lol Sometimes this will lead to your fish spitting it out or just ignoring it altogether. I accidentally poked a hole in a bag of frozen bloodworms breaking chunks of them up which led to freezerburn...my puffer refused to eat from that bag unless he was really hungry. Immediately after giving him some of the fresh bag there was no hesitation to munch away.

I really like freeze dried krill for most of my big fish. The krill is hard to swallow without a bit of gumming and softening and it's not very dense, so my fish can eat as much as they want without over stuffing themselves. I used to use Hikari carnivore sticks and these are the opposite. They're very dense and swell up in my fish's stomachs allowing them to get too full.

Krill is very nutritious too, and it's vitamin enriched. Even my pleco loves it.