They are a shoaling fish so aim for at least 6. They stay very small.
They don't eat all kinds of algae though. They like fresh green algae most of all! I can almost guarantee they will need extra feeding from things likeVa blanched sliced of zucchini or cucumber, or some like blanched spinach or curly green lettuce, along with algae wafers. They are best fed at night after the lights have been off a little while and the rest of the fish (corys aside) aren't so actively looking for food.
They're picky little fish and can drop dead for no obvious reason, but quite cute in the meantime.