Crossocheilus siamensis, the true Siamese Algae-Eater

Crossocheilus siamensis (Siamese Algae-Eater). When you are squinting at this, barely an inch long, in the LFS, trying to decide whether you have the "good" Siamese Algae-Eater, the one that will eat hair algae or thread algae, which no other fish will touch, apparently, and that will even nibble on your redbeard algae (Audouinella sp), you'll be glad to have a few diagnostic points, which you should memorize right here and now. First of all, the fish you're looking for, the genuine Siamese Algae-eater, has clear unmarked fins, though they might have a faint milky bloom in an angled light; if that dorsal fin has a black splotch, the fish is Epalzeorhynchos kalopterus (Flying Fox), a charming enough fish itself, but not the devoted algae-eater you're hiring. Then, the true SAE's black lateral stripe should have a ragged, zigzag upper edge, not a clean straight one, and the stripe should extend all the way onto the caudal fin. On the fishes' upper side, above the stripe, the scales are edged with black, which gives it a delicate net-covered look. If your eyes are better than mine, you may be able to distinguish on its snout the rhynal lobes that mark Crossocheilus as a species distinct from Epalzeorhynchos and see that it has one pair of barbels, not the two that Epalzeorhynchos sports.
 
Diagnostic points. Clear dorsal fin, ragged-edged black stripe extending onto the tailfin, black-edged "netted" scales, rhynal lobes. Got all that? You will be quizzed. This material will be on the mid-term. The ultimate article on C. siamensis and the four impostors that are most commonly switched for it was written by Neil Frank and Lisa Sarakontu in 1994: "Algae-eating cyprinids from Thailand and neighboring areas". 
 
In 1997 I heard from a post at Aquatic-Plants mailing-list that there are three Crossocheilus species in West Borneo that are superficially identical to the C. siamensis we see in the U.S. aquarium trade, all of them  illustrated in Tyson R. Roberts, Freshwater Fishes of West Borneo  (Proceedings of the California Academy of Sciences, 1989) , a volume I still haven't seen  (second-hand copies starting about $125). Could it be that some species are more willing black brush algae-eaters than others? Could some be more aggressive than the ordinary C. siamensis? Most imports come from Thailand, but do we have in our tanks some unrecognized "Borneo Algae-Eaters" (I hesitate to introduce the term) from Indonesia, perhaps imported through Singapore, as Clown Loaches are? Liisa Sarakontu and David Whittaker were discussing "Crossocheilus oblongus" and other species and the possibilities of SAE look-alikes, in the Aquatic-Plants mailing-list, 14 Sept 1997 etc. "One of the local importers once boasted that his SAEs are from Borneo," Liisa Sarakontu noted, "but I didn't believe him at that time because he didn't bother to check anywhere, and he didn't seem to take my questions seriously. All the other importers have either said that they are from Singapore or 'it is a secret'."
 
These fishes are usually sold pretty small, about an inch, but don't cramp this species too long in a tank that's too small. When I first wrote this note, I'd just bought one that was not more than an inch total length. It was handling the algae in a planted 10-gallon tank, but I was recommending that within a matter of months it would need at least 20 gallons to grow to its full size, slightly over 5 inches (14 cm or so). But it grew to a good size right there, in the densely planted ten, where water changes keep the nitrates <20 ppm and it had the company of a flock of female Fundulopanchax gardneri. (It was since turned loose in a 30-gal tank and lived to be fully ten years old.)
 
Robert Paul H suggests that you keep yours in groups. To imitate him and keep the Siamese Algae-Eaters as a trio in a large planted aquarium was a pleasant plan I put into action; the last of the trio died in 2010. I currently have two half-grown ones in a 10-gallon tank of Microsorium pteropus, which had become disastrously overrun with black brush algae that Otocinclus wouldn't touch, following a hot weather meltdown; they are eliminating it because I'm keeping the flake feed rations rather spare. To see the constant company they keep, checking in with each other, convinces you that one kept all alone cuts a sad figure. Robert Paul H has a good article on C. siamensis at Aquabotanic, where he notes that this hard-working fish will also eat planaria (flatworms). He notes that the species is only seasonally available in your LFS. In their home waters the fishes spawn in the spring and early summer monsoon floods, and the inch-long young are caught when the waters have receded in autumn, Lisa Sarakontu pointed out in a post to the Aquatic-Plants mailing list, July 1999. Robert Paul H emphasizes that this species is more agreeably social than any of its scrappy relatives. 
 
Even more exciting is the news that they have been successfully spawned, by Dave Underwood, who reported to the Aquatic-Plants list some details of six 1996 spawnings of Siamese Algae-Eaters, some of them actually intentional! Though his pH ranged from 6.5 to 7.6, his water was fresh and often renewed. Though the tanks ranged from a 10-gallon to 90 gallons, they were all heavily planted. The fishes spawned as a group, scattering eggs in the plants and eating them. To get them started, he simulated a flood season with water changes of almost 95%, provided brisk current and also some calm eddies where spawning occured in Java Moss and other plants. His April 1997 e-mail to the Aquatic-Plants list has even more detail.
 
At a quick glance, our North American Black-Nose Dace, Rhinichthys atratulus, looks so much like the SAE (they are only distantly related) that it would seem there is survival value in the sleek torpedo form with a bold black stripe. Yet another unrelated look-alike is the South American hemiodid characin Parodon pongoense, also an algae-eater according to the Baensch Atlas, and worth importing, I'd think,  for that virtue alone.