Bex -- I think I have a small, maybe stunted, specimen. Others who have kept this fish have seen it get a lot bigger in the same time. Possibly the tanks it has been were too small or too overcrowded? Or else I haven't been feeding the same high protein stuff that others have? She really does get mostly veg and wood, as seems to be correct according to the wild fish. She is healthy though, and tame, so I don't think there's anything wrong with her. And yes, I'm very attached to her. I agree that Panaque spp. are different. I can't figure out why. But I think it is their arched back, which makes them look more like a land animal than a fish, and also those big flippers they have instead of fins. I have to resist the temptation to stroke her, she looks so tactile and such a nice handful of fish. Years ago I had a blue-eyed plec, and that was similar. Sadly, I didn't really know what I was doing back then, and it only lasted a year or two. Now you can't find that species for love or money!
Crossfc -- Sounds exactly as if the ammonium is the problem. Just to be sure, don't feed the fish tonight, and then do an ammonium test tomorrow morning before you feed them. If there's still ammonium in the system, do a 50% water change as soon as you can, and repeat every day or two. Until the filter gets fully matured, the ammonium is a serious threat to your Panaque. They aren't fish for immature aquaria. As you've probably gathered by now, these are seriously amazing fish that everyone falls in love with, and they are well worth the effort. Raising the pH isn't difficult. Either add something calcareous (e.g. coral sand) to your filter, or else buy some pH buffer from your aquarium shop and use as indicated on the package.
What's the pH of you tap water? Is there ammonium in the tap water to begin with? Sometimes, if the water is treated with chloramine as well as chlorine, you can get a bogus reading of ammonium (I believe, others may know for certain).
Cheers,
Neale
PS. LisaLQ -- I don't feed my fish just wood, but also vegetables. What they don't need is high protein food. Here's some more stuff Hiro Nonogaki sent me:
Brazilian populations, like from Rio Xingu, Tapajos, or Tocantins, do not live in tanks so long (i.e. no more than 5 years) because people feed too much calorie to them. Specimens I dissected accumulate too much fat around all organs inside of the fish, but the stomach is empty most of the time. I never seen this in the wild. Just not a good idea to feed too much fish food or animal products to P. nigro. I recommend to feed something like spirulina, Chlorella, soy protein, and etc. It is not confirmed but I think they do have nitrogen fixing bacteria in their GI tract, so as long as fish eat wood, people do not have to worried too much about their food.
In the wild at least, the stomach is filled with wood at all times, and they can use this to grow, as has been proved by experiments in labs. There's more here:
http
/www.towson.edu/~nelson/Panaque/pqpap-abst.html
I got a long time to wait! Eddie is only about 5-6". So it's pretty difficult to sex these guys then? Oh well, Eddie will be a he in my eyes. 
I think the ammonia is from me feeding my fish a little while before testing the water. 
