I personally think the tank size would be fine with proper filtration... However, they will try to eat EVERYTHING. They aren't fast enough to catch faster fish that are higher in the water, but anything on the bottom will be pecked at constantly. Unless you can be sure of their strain (buy from a breeder not a pet shop) you will likely get the flatter type that grow very large. The true round pearlscales are hard to come by just by luck because they have more trouble spawning.
Mine are quite small, but they still pick up gravel and move it around searching for food. You can always hear the rocks scraping the bottom and hitting the sides.
I love mine to death, but I wish I had not gotten them now because of how many problems they have. That cute little round ball of a body comes at a heavy price in health... Swim bladder issues are guaranteed, as is constipation. They also have a tendency to bloat or develop dropsy but you can't tell because of their body shape and scales.
Everytime mine look slightly rounder than normal I start to worry...