I have small schools of both in my planted tanks. All the pygmies are indeed very shy, even in larger groups. They are about 1" fully grown. The habrosus are a bit larger but MUCH more active and outgoing for me. Both are kept in similar water (and it's pretty hard with pH over 8 in most of my tanks). Both scavenge well and will eat about anything that hits the bottom. Both have been very hardy fish for me as well. If I buy more, it will be the habrosus, though, because I enjoy their antics and the fact I actually get to see them!