Chilodus punctatus, the Spotted Headstander

Chilodus punctatus ("kye-LO-dus:" toothy lips)   Spotted Headstander). Here's an underestimated fish that's widely distributed in the weedy backwaters of the Amazon basin, in the Tocantins, Rio Negro and the Orinoco, even in Guyana, where it was first collected in the 1840s  "from the standing waters of the savanna". That should give you a hint of the weedy waterways you want to reproduce in their aquarium, perhaps even littered with fallen leaves. I have pasta boxes of brown leaves of Cutleaf Beech stashed since last autumn for situations like this.  The various populations have some local differences.
 
Chilodus is a biofilm grazer like the Nannostomus species, and it needs to be constantly supplied with some vegetable supplement. It isn't easy to keep the Spotted Headstander in robust condition; the fish will take flake food and algae wafers, and vegetables to supplement their algal pickings.  An analysis of stomach contents of Chilodus punctatus in the Yucao River, Colombia, found that the greatest percentage, varying seasonally, consisted of diatoms, filamentose and siphonales algae, with some rotifers and even cyanobacteria.  In the aquarium their constant but choosy pick, pick, pick over leaf surfaces tends to farm diatoms, not eliminate them.
 
Chilodus punctatus, one of  four species in the genus, has sometimes suffered from getting confused with a moderately closely-related headstander, Abramites, which does have a well-founded aggressive reputation. I have found these shy and gentle fish to be subtly competitive among themselves, not unlike Nannostomus. Though the Baensch Atlas (v.I, 318) says that they're found in schools, I notice a change in their behavior within a few days, even with shipments that have arrived in dealers' tanks. Schooling is largely a fright reaction, I think. Perhaps the fin-flaring and body-shimmying that I witness may just presage early jockeying towards some pre-nuptial condition. Surely they're much more interesting if you keep them in a group of three or four, well matched for size. 
 
Breeding Chilodus punctatus. Spawning has been very occasionally achieved in aquaria — Rolf Geisler gave an account in Tropical Fish Hobbyist as long ago as Aug. 1959 — but not yet on a commercial scale. Not enough market pressure for them, I imagine. In the U.S. at least, the fishes you buy are likely to be wild-caught. They will probably arrive home starving, but too frightened to eat. Try to avoid purchasing individuals with very flat, knife-thin abdomens. They may be suffering from intestinal nematodes, too, so they bear careful watching in a full-length quarantine that includes pre-emptive de-worming medication, because most Neotropical fishes arrive carrying their natural load of gillworms.
 
The fish are at home in a well-planted aquarium, with open space to move around in but some dark shadowed places near at hand, suitable for a moment's refuge, and with the added security of drifting green plants overhead. Soft water filtered with some peat is preferred. Tannins and low pH tend to reduce the bacterial load; these fish are prone to finrot and intestinal problems if they don't have constant greens.
 
They won't thrive with boisterous tankmates. In sympathetic surroundings, the silver of their body color will become suffused with rosy golden and olive tones as they mature. Each scale has a warm black blotch at its base and is delicately outlined with black to create a subtle all-over reticulated patterning. The bold lateral stripe is inky black. The eye is rosy red. But it's the obliquely vertical stance of these fishes that makes them memorable.
 
Links. Aside from abbreviated entries in catalogs of  fish species, there's not much. The Aquaworld website has some useful detail.
 
Chilodus punctatus at Wikipedia.