Every species

The striped barracuda tetra, Acestrorhynchus isalineae, is a small predatory acestrorhynchid from the rio Madeira basin in the Brazilian Amazon. Most records come from the type locality, a tributary of the rio dos Marmelos. Like others in the A. nasutus group it keeps two dark longitudinal stripes into adulthood and stays around 100 mm. Acestrorhynchids are cannibalistic given the opportunity, so a group must be of comparable size.

The pike tetra, Acestrorhynchus microlepis, is a predatory acestrorhynchid from northern Amazon drainages and the Orinoco. It also occurs in coastal rivers of Guyana, Suriname and French Guiana. A member of the A. microlepis group, it has a small blackish spot behind the gill cover and is separable from the very similar A. grandoculis only by counts. It tends to take smaller prey such as tetras, and acestrorhynchids are cannibalistic, so a group must be of comparable size.

The Pantanal barracuda tetra, Acestrorhynchus pantaneiro, is a predatory acestrorhynchid from the Paraná, Uruguay and de la Plata basins. It also occurs in the rio Mamoré in Bolivia. A member of the A. lacustris group with a round humeral spot, it is virtually impossible to tell from its relatives in the trade unless collection data is known. It lives in open water, and a group must be of comparable size because acestrorhynchids are cannibalistic.

The giant Chinese bitterling, Acheilognathus macropterus, is a bitterling from China, the Korean peninsula, northern Vietnam and southeastern Russia. It has been introduced to Japan and is considered invasive there. Typical adults are 100 to 150 mm, and it appears in the trade only irregularly. Like all bitterlings it spawns in living unionid mussels, and its wide range suggests it may be a group of closely-related species.

The sheep pacu, Acnodon normani, is a serrasalmid from Brazil, possibly restricted to the Xingu and Tocantins watersheds of the Amazon basin. Also known in the trade as 'tiger pacu', it is often said to be a frugivore or herbivore, but aquarium observations suggest it also feeds on the scales of other fishes. That makes it unsuitable for the community aquarium, although it does not seem to target much smaller species.

The half-banded loach, Acoura savona, is a nemacheilid loach from Ganges tributaries draining the eastern Himalayas in India, Nepal and Bangladesh. The species is seen in the trade fairly often and is sometimes sold as 'bicolor loach' in the United States. Its colour pattern of 9-10 thin, yellowish bars on a dark upper body, with plain whitish lower parts, separates it from similar loaches, and it is among the less aggressive of them.

The falcate chameleon catfish, Acrochordonichthys gyrinus, is an akysid catfish known only from the Yom River, Chao Phraya basin, northern Thailand. A concave rear margin to the pectoral fins separates it from the rest of the A. ischnosoma group. When stressed it can secrete a milky substance from the axillary pore that quickly kills other fishes in an aquarium, and smaller tankmates will be eaten.

The Asian banjo catfish, Acrochordonichthys rugosus, is an akysid catfish from Java, Sumatra, Borneo, Peninsular Malaysia and southern Thailand. The most commonly encountered member of the genus in the trade, it is still by no means common, and body colouration varies widely even among fish from a single locality. Like its congeners it can secrete a milky substance from the axillary pore when stressed, and this can quickly kill other fishes in the confines of an aquarium.

The Mae Klong chameleon catfish, Acrochordonichthys septentrionalis, is an akysid from western Thailand, possibly endemic to the Mae Klong drainage. It differs from other members of the A. ischnosoma group in its almost uniformly cream body with a few small brown spots, though colouration in the genus is variable. Like its congeners it can secrete a milky substance from the axillary pore when stressed, and this can quickly kill other fishes in an aquarium.

Acrossocheilus beijiangensis is a barred cyprinid from Fujian, Guangdong and Guangxi in southern China, plus the islands of Hainan and Hong Kong. With A. clivosius it is one of only two species in the genus always to have five dark vertical bars on each flank. Wild fish feed on small benthic invertebrates and graze biofilm from rocks and other solid surfaces.

Acrossocheilus iridescens is a barred cyprinid known from Laos, northern Vietnam, Yunnan province in southwestern China and Hainan Island. Adults carry wide black vertical bars on the flanks, each six to eight scales across, and lack the filament on the dorsal fin seen in its closest relative, A. longipinnis. Some populations are of questionable taxonomic status, and the species sensu stricto may be restricted to Hainan, where the type locality lies.

Acrossocheilus monticola is a barred cyprinid that is apparently endemic to the upper Yangtze River basin in China. It alone in the genus has seven or eight dark vertical bars on each flank, each one to three scales wide. The type locality is a mountain stream flowing into the Ichang gorge, and wild fish feed on small benthic invertebrates and graze biofilm from rocks and other solid surfaces.

The Taiwan banded barb, Acrossocheilus paradoxus, is a cyprinid native to Taiwan, where it occurs throughout western and northeastern river drainages. It inhabits subtropical streams and small to medium rivers at medium to relatively high altitudes, and in the aquarium needs spotless, well-oxygenated water with moderate flow. Growing to around 200 mm SL, it needs a tank of at least 180 x 45 cm.

Acrossocheilus parallens is a barred cyprinid from Guangdong and Hainan provinces in southern China, plus the island of Taiwan. It has five or six dark vertical bars on each flank, each two scales wide, a pattern it shares with A. paradoxus and several other congeners. Wild fish feed on small benthic invertebrates and graze biofilm from rocks and other solid surfaces.

The saddle cichlid, Aequidens tetramerus, is a cichlid found across much of northern South America, from the Amazon and Orinoco basins to the Guianas. The type species of its genus, it occurs in several colour forms, and fish from Ecuador and Peru are sought after for the red or orange colouration on the lower head and belly. As currently recognised it is likely to represent a group of related fishes, some of which may be described as distinct species.

The spotted talking catfish, Agamyxis pectinifrons, is a doradid catfish from the Amazon basin in Bolivia, Brazil, Colombia and Peru. Very common in the trade, it is hardy and relatively long-lived, and recommended to beginners and experienced aquarists alike despite its adult size. It closely resembles A. albomaculatus, known only from the Río Orinoco drainage in Venezuela, and the two are probably sold under the same trade names.

Ageneiogarra imberba is a cyprinid without barbels from the upper Yangtze, Mekong and Red River basins in southern China, and the upper Red in Vietnam. Records from the Salween system result from confusion with the similarly-named Garra imberbis. With Garra micropulvinus it is placed in the Semilabeoina. It tends to inhabit swiftly-flowing headwaters and tributaries.

Ageneiogarra theunensis is a large cyprinid from the Nam Theun and Nam Gnouang systems of the Mekong watershed in Laos, and the Nan River in Thailand. It grows to 300 mm SL and has a plain brown body and fins, sometimes with 6-8 faint longitudinal stripes. It tends to inhabit swiftly-flowing headwaters and tributaries with clear, oxygen-saturated water.

The manduba, Ageneiosus inermis, is a large auchenipterid catfish found throughout much of South America east of the Andes. At around 470 mm SL it would need an aquarium in excess of 400 x 120 cm as an adult and is largely unsuitable for private aquaria. An obligate carnivore, it can take surprisingly large prey, and the larger Ageneiosus species are often used as food fishes in their native countries.

The bottlenose catfish, Ageneiosus marmoratus, is a predatory auchenipterid catfish from Guyana, Suriname and the upper Amazon in Peru and Ecuador. Also sold as 'Guyana slopehead', 'dolphin' or 'hammerhead' catfish, it loses much of its black-blotched juvenile patterning as it grows. Surprisingly peaceful with anything too large to swallow, it is active and sometimes skittish, and needs a tank of at least 150 x 60 cm.