Pangio kuhli, the eel-like Kuhli Loach

Pangio (Acanthophthalmus) kuhli. (Kuhli Loach). For tiresome technical reasons we're meant to get used to referring to this species as Pangio. I'll admit "Acanthophthalmus" was a mouthful, but at least it did mean "spiny-eye!" The genus Pangio is a large complex of overlapping species, "sub-species" — whatever that might genuinely mean nowadays — and populations.
 
Kuhli Loaches have a wide distribution in Thailand and Malaya, Sumatra and Java. Various other Pangio species that we don't see in aquaria range westwards as far as northern India and east to Kalimantan (Borneo). In the males, the second ray of the pectoral fins is supposed to be thickened: I could never see this myself, but Gunther Sterba's Freshwater Fishes of the World (1967) mentioned it.
 
Try keeping Kuhli Loaches at a slightly cooler temperature, 70° to 75°F. They'll appreciate the greater dissolved oxygen at the lower temperatures.
 
Breeding. Kuhli Loaches are the tropical loaches that have reproduced most often in captivity, though nobody ever seems to catch them doing it. They bred for Al Castro in soft water with a pH ranging 6.3 to 6.8. Castro had five spawnings that produced young. Though he claimed to have learned little from the events, he noted that the greenish adhesive eggs were scattered through plants, especially Water Sprite. The fry pretty much raised themselves undisturbed, in a natural planted aquarium with plentiful sub-microscopic life. Al never saw any sign of a bubblenest, which has sometimes been credited to Kuhli Loaches. His account was published in  Aquarium Fish. In each reported case of a surprise Kuhli spawning, the crucial elements seem to be the security and privacy offered by constricted cave-like openings and the company afforded by a fairly large colony. You wouldn't want to keep Kuhli Loaches alone anyway, not once you've seen how tactile and sociable they are. Gregarious. These are crepuscular fishes, but they lose their twilight habits if you give them plenty of opportunities to hide in tight shadowy spaces. Then they'll drape themselves like tree snakes in dense plant growth.
 
Kuhli Loaches would rather live in an undergravel filter than almost any more picturesque set-up you can contrive, and I've known them to disappear for years, to be forgotten, and to reappear, wriggling with alarm, only when the undergravel filter was being siphoned or the tank was being taken down.