my betta does this too lol
at first i thought he was eating the pellets too quickly and not giving them the chance to soak up some water and soften, so he would wolf the first one down as soon as it hit the water, but then spit it back out
now before i put his pellets in, i fill the pellets lid up with a little of the aquarium water and leave 3-4 pellets in there for a minute or to two to get soft
he really goes to town on them once i throw them in
