Another example of the LFS guy not giving accurate info! They are big enough for flake food because flake food is thinner than paper and when eaten it's volume is extremely small. Pellet food comes in several sizes and when soaked becomes soft and they probably can eat that, too. Frozen brine shrimp, on the other hand, has almost no food value and while feed by almost every hobbyist it should be fortified with Selcon or Zoecon before being feed. Get some flake food and some tiny pellet food and let the fish determine whether it's of suitable size. Frozen Mysis is better than frozen brine shrimp although I feed both after soaking to enrich them.
Dick