I've noticed this with my new Aquabid boys and the Tiny Yellow Submarine. I feed all my fish New Life Spectrum pellets and the amount usually vary based on the fish's size. Tiny refuses to eat more than 2 NLS pellets, and he's a pretty big fish. Which sometimes worries me.
Castiel sometimes will eat 4 NLS pellets like he's been starved his whole life, and at other times, he will slowly chew up his pellet spit it back and eat it, or not eat at all. The same is for Jericho. This is not a recent discovery. Periods of chowing down and refusing to eat vary. I have definitely seen them eat before and will chow down bloodworms, but I really would like to keep them on a healthier diet.
My assumption is that they were fed live food back at their old home. I put a bucket of green water outside in hope that some mosquitoes would lay their eggs there.
Could the NLS pellets also be too old? I've only had them for about 2-3 months though. However, my dog has eaten half the container and there was some dog spit in there. I tried to clean most of it out though I may have missed some. Could this affect their behavior in any way?