PlanetCatfish.com

I didn't know if I should bother with an ID since he's completely malnourished, his stomach couldn't get any more concave.
I thought I'd give it a shot anyway and see what comes of it.

I've noticed these for sale at one of the LFS. They're being sold as Giant Oto's for about $7 each. They seem to be closest to what's listed as Sp. 2 in the Cat-eLog. Doesn't seem to be a lot of information out there about them so I hadn't decided yet if I was going to try a few of them. I'm assuming due to their physical characteristics that they'd do well in a tank that could also support Otocinclus, Farlowella, etc.?

yes.

best way to keep Hypoptopoma's is in a group in a wellplanted tank wich also has a few pieces of softer bogwood.

they're incredable algae-eaters, but they're also shy and not nearly as visible as Otociclus. they like to move at dawn, dusk and night, but they usually hide when the tank is brightly lit; hanging on the underside of bigleafed plants or rootwork.

They like algae a lot but also accept weighed-down cucumber, pleco-tabs, regular flake, daphnia, cyclops, mysis etc.
don't overcrowd the tank! this is not a fish that will "fight over" a piece of food with a horde of tankmates; if it has to compete with loads of other fishes it can and does starve to death.

take care with tankmates; they don't like to be chased or picked upon; agressive cichlids or territorial Loricariids should be avoided.
you can waste a nice bunch of Hypoptopoma's by adding 1 belligerent Panaque LDA01, Chaetostoma spp or Hypostomus cochliodon etc.
they do fine with easygoing tankmates; Corydoras, smaller characins, Farlowella, Rhineloricaria's and really peaceful cichlids like Dicrossus filamentosus etc.

I thought H. sp. 2 looked closest as well. $5 where I bought him.
A damn shame. He died early this morning. I felt terrible for the little guy. His stomach was grotesquely sunken in. He'd flop about when he tried to move and land in whatever position he happened to be in. A gorgeous fish, just wish I had found him, and the rest of his tankmates, a whole lot sooner.
When I bought him I asked to buy however many were left in the tank and the guy said he thought he had two or three besides the one I'd seen. When he moved the decor over all kinds of bones, spines and scales came swooshing out, "oops, no, I guess it's just the one" . Absolute pity.

Thanks sid. Will come in real handy should I come across them again.