Every species

Luciosoma bleekeri is a slender, pike-like cyprinid from the Mekong in Laos, Thailand, Cambodia and Vietnam, and from central and western Thailand. Subadults are traded regularly as 'apollo shark' or 'shark minnow' and it is frequently confused with L. setigerum, which has a series of black spots on the lateral line scales that this species lacks. It needs the largest private aquaria, and feeds mainly on terrestrial insects taken at the surface.

Luciosoma pellegrinii is a slender, pike-like cyprinid endemic to Borneo, ranging from the Kapuas in West Kalimantan to Sabah. It is scarcely known in the aquarium trade because it comes from an area where very few commercial collections take place, but its name is misapplied on a regular basis. It has 4 to 8 distinct dark spots on the lateral line and appears to develop longer pelvic-fin filaments than any other member of the genus.

The apollo shark, Luciosoma setigerum, is a slender cyprinid found across much of Southeast Asia, from the Mekong basin to Borneo, Sumatra and Java. Subadults are traded regularly and are frequently confused with L. bleekeri, which lacks the series of black spots on the lateral line scales. A similar fish of unknown origin with no stripe on the front of the body is also common in the trade, listed as L. cf. setigerum. It needs the largest private aquaria.

Luciosoma spilopleura is a small cyprinid known only from Sumatra and the Indonesian part of Borneo, where it prefers fast-flowing headwater streams. The species is poorly known and is not present in the ornamental trade, although its name has been widely misapplied to other Luciosoma species for decades. The largest known specimen measured 81.9 mm, so it appears to grow much smaller than its congeners.

The red-finned pike cichlid, Lugubria johanna, is a large pike cichlid that ranges over much of northern South America. It is known from the Orinoco, Essequibo, Oyapock and Approuague basins among others, mostly in faster moving rivers and streams, and a number of colour forms have developed across its range. Growing to 30 cm, it can be aggressive, especially towards its own kind, and will eat any fish small enough to be considered food.

The Atabo red pike cichlid, Lugubria lugubris, is a large pike cichlid from rivers in Suriname, Guyana and Brazil. Colourful when small, it quickly grows into an aggressive adult of up to 40 cm and will eat any fish small enough to be considered food. Pairs are difficult to form because males become increasingly aggressive as they mature, and prospective mates are often killed.

The striped pike cichlid, Lugubria strigata, is a large pike cichlid from the lower Amazon basin in Brazil, away from the main river itself. One of the more commonly available pike cichlids in the UK, it is often bought by fishkeepers unaware that it grows to around 40 cm. It can be aggressive, especially towards conspecifics, and is reported to be susceptible to hole in the head disease.

The tiger pike cichlid, Lugubria tigrina, is a pike cichlid known only from the Rio Trombetas in the Brazilian Amazon. It is rarely seen in the UK hobby, and males carry the prominent black spots and stripes behind the common name. Growing to around 30 cm, it can be aggressive towards conspecifics and will eat any fish small enough to be considered food.

The giant sword minnow, Macrochirichthys macrochirus, is a large pelagic cyprinid widespread in Southeast Asia, from the Mekong to Borneo and Sumatra. Growing to 600 to 800 mm and becoming increasingly piscivorous as it grows, it is unsuitable for the majority of private aquaria, although juveniles are traded on occasion. It is thought to have been extirpated from the Chao Phraya, Mae Klong, Lake Songkhla and Java, and the Mekong populations have been drastically reduced.

The zebra spiny eel, Macrognathus zebrinus, is a spiny eel from Myanmar, found in rivers and swamps with large amounts of aquatic vegetation. It was previously included in the closely related genus Mastacembelus. The sharp dorsal rays that give spiny eels their name can easily puncture human skin. Peaceful with fish it cannot swallow, it tends to be territorial with its own kind and grows to 460 mm, although usually smaller in aquaria.

Macropodus erythropterus is a paradisefish from coastal hill streams of central Vietnam, in Quang Binh and Quang Tri provinces. Occasionally traded, sometimes as 'red-backed paradisefish', it is often misidentified as M. spechti, which lacks red in the dorsal, anal and caudal fins. Whether the two represent the same taxon has been debated. A bubble nester, it is relatively peaceful unless breeding.

Macropodus hongkongensis is a paradisefish from Hong Kong and the neighbouring Chinese provinces of Guangdong and Fujian. In Hong Kong it is now known only from Tai Po and Sai Kung districts. It lives in hill streams and lowland, sometimes agricultural, habitats, apparently preferring shallow, densely vegetated water with slow flow. Males are territorially aggressive, especially when breeding, and the species is a bubble nester that is occasionally available in the trade.

The roundtail paradise fish, Macropodus ocellatus, is a labyrinth fish with an enormous range in China, Korea and Japan, north to the Amur River. It lives in ditches, rice paddies, marshes and river backwaters, where winter can freeze the surface and drop the water to 3 °C. It is sometimes referred to as M. chinensis in older literature, a name now considered a synonym of M. opercularis. Males are territorial when breeding and build bubble nests.

The paradise fish, Macropodus opercularis, is a labyrinth fish from China south of the Yangtze, including Taiwan and Hainan, plus Vietnam and Laos. Imported to France in 1869, it was among the very first ornamental fish brought to Europe. Wild examples are uncommon in the hobby since it is farmed extensively, and xanthic, albino, red, blue and stripeless strains exist. Males are territorially aggressive, especially when breeding, and should not be housed together unless the aquarium is very large.

The black paradise fish, Macropodus spechti, is a labyrinth fish from central Vietnam, known with certainty from the Thu Bồn and Hương river systems. Its name is frequently misapplied to the similar-looking M. erythropterus, easily identified by reddish pigmentation in the dorsal, anal and caudal fins. Older literature sometimes refers to it as M. concolor. Relatively peaceful unless breeding, it is kept in pairs.

The diamond tetra, Makunaima pittieri, is a characid endemic to Lake Valencia and surrounding waters in Venezuela. It is usually sold as a fairly bland, silvery juvenile, and given time and a good diet develops into an adult that sparkles like a diamond. It is found in shallow, vegetated parts of the lake and slow-moving tributaries, but most fish in the trade are mass-bred on commercial farms in Eastern Europe or the Far East.

The ornate paradisefish, Malpulutta kretseri, is a labyrinth fish from the 'wet zone' of southwestern Sri Lanka. It has been recorded from the Gin, Kelani, Kalu, Nilwala and Bentota river basins. The only member of its genus, it is protected by law in Sri Lanka although it still appears in the aquarium trade from time to time. Three colour forms exist, differing in the amount of reddish, violet or bluish pigmentation in the fins.

The Celebes rainbowfish, Marosatherina ladigesi, is a rainbowfish from the island of Sulawesi (formerly Celebes) in Indonesia. For many years it was included in Telmatherina, and it is the only species in Marosatherina. Overfishing for the aquarium trade has left it listed as vulnerable by the IUCN, but it is now mass-produced on farms in the Far East and Eastern Europe. It needs pristine, medium to hard alkaline water and is very sensitive to rapidly changing conditions.

The silver cichlid, Maskaheros argenteus, is a large Central American cichlid that appears to be endemic to the River Usumacinta drainage in Mexico. Also called the white cichlid, it is aggressive, especially towards conspecifics. It may be kept with other tough Central American cichlids if enough rock and bogwood forms territories for all, but there is no guarantee of success.

Regan's cichlid, Vieja regani, is a large cichlid endemic to the River Coatzacoalcos basin in Mexico, where it lives in rocky rivers. Uncommonly seen, it can be a challenge to accommodate, and it is not uncommon to end up keeping these fish individually. It was previously described as Cichlasoma regani and is still occasionally sold under that name.