Order Siluriformes
Family Loricariidae
Subfamily Hypoptopomatinae
Genus Acestridium
— Acestridium dichromum [Retzer, Nico & Provenzano, 1999]. (Eng. Green Whiptail). South America: Venezuela, Brazil, in the upper reaches of the Orinoco, Rio Casiquiare, and Rio Negro rivers. They live in coastal vegetation and among the branches of fallen trees, mainly in flowing areas in clear water with acidic values. 6 cm. The body is very slender, the dorsal fin is located far back, and the adipose fin is absent.
This fish is unusual among catfishes for its captivating neon-green coloration. The uniqueness of A. dichromum lies in its ability to change color from brown to light green. Peaceful, they should not be kept with large and aggressive fish species. These fish often sit motionless for a long time on pieces of wood, plant stems, and aquarium glass, making them difficult to spot.
Aquarium maintenance is quite problematic. The aquarium should be planted with live plants; they feed on algae fouling. Driftwood and large rounded stones are also desirable. Water should be clean and acidic, with strong filtration current. They spend time on driftwood, plants, stones, or the side walls of the aquarium scraping off algae, and very rarely on the substrate.
This makes feeding them difficult. They feed on algal fouling and rarely accept sinking tablets, so a constant supply of stones with algae growth must be provided, otherwise they will perish. Nevertheless, they will eat Artemia nauplii if they gather on the aquarium glass. pH 5.5-7.0; dH 2-12°; T 23-27°C.
Genus Hypoptopoma
— Hypoptopoma thoracatum [Gunther, 1868]. (Eng. Flat Head Dwarf Sucker). Brazil, Rio Negro, Xepero River. 6-9 cm. Body elongated, torpedo-shaped. Head elongated, strongly extended, snout pointed. Mouth inferior, sucker-like. Very reminiscent of Otocinclus. Greenish-gray with a shiny border along the scales and brown eyes. Coloration: back and sides brown, with whitish specks and a shiny border along the scales, belly light.
Peaceful solitary fish, though it may form small groups. Can be kept in a general community aquarium with any non-predatory fish. Nocturnal by nature, but once accustomed to captivity, it can also be active during the day. Substrate: coarse sand. Timid, needs plenty of hiding places. Vegetation and driftwood are a must to provide ballast and cellulose essential for digestion. Does not damage plants. Does not require a strong current. pH 6-7.5; dH up to 12°; T 22-28°C.
— Hypoptopoma gulare [Cope, 1878]. Synonyms: Otocinclus, Hypoptopoma joberti, Aristommata, Hypoptopoma inexpectata, Diapeltoplites gulare. Peru, Amazon basin. 8 cm. Coloration olive-gray or beige with grizzling and dark spots across the body. Fins with rare black spots and streaks. Dorsal and caudal fins with a black margin. T 23-26°C.
Identification: Genus Hypoptopoma
Genus Macrotocinclus, Genus Oxyropsis, Genus Schizolecis.
Pseudacanthicus leopardus, spinosus. 
