Yes, but it is safest to defrost any frozen foods in a little container with a bit of tank water. I use the little bathroom plastic drinking cups, easy to recycle.
You can cut a cube in 4 slices and use a half of that (1/8th) or if they are really hungry a slice. The trick is feeding well, but not too much food. For instance it would be better to feed a 1/8 2x per day than 1/4 one time type thing.
Reasoning is too much food is wasted and can "up" ammonia and lead to poor tank water.
You could try frozen in AM so they have all day to eat it, and pellets in eve. They really probably shouldn't have that high protein only. Make sure they get something with veggie matter too. For good digestion.
Keep up with water changes and good feedings.