While many aquarists value Otocinclus catfish as algae eaters, they seems to be looked on more as a part of the tank maintenance system than as "pet fish". And quite frankly, my impression of them was that they just weren't the most exciting fish. While I found them interesting, they never seemed to do much. So I was intrigued by an article in the February issue of Tropical Fish Hobbyist by Gary MacDonald. Not only did he say that they are very social fish, he also spoke of interesting dominance hierarchies in groups of 12 or more. While this caught my attention, I didn't feel like I had room for another dozen or so fish in my main tank. With the former Macropodus tank available, I ended up buying some, pretty much on a whim.
From what I've read, one of the major concerns about pet store Otocinclus is that they are often starving - they are herbivores, and are likely not to have had enough to eat for a while. There is also the stress involved in being caught and transported home. Once I got them into their tank, they all went for the bottom or the sides of the tank and just suck there. But after a few hours they were extremely active, swimming all around the tank, presumably examining surfaces for algae. They have slowed down a little since then, but they remain much more active that any Otocinclus I have seen previously. Of course, they are also very young - I wouldn't be surprised is they slowed down a lot as they matured. It'll be interesting to see what happens.