Every species

This species was introduced into the aquarium trade in the early 20th century but disappeared soon after. It subsequently reappeared in a Berlin zoo in 1965 and has been available from specialist breeders ever since. It occasionally appears for sale in aquatic shops....

Also known as the salmon-red or New Guinea rainbowfish, this is one of the most popular rainbows in the hobby. Unfortunately, the colouration of today's mass-bred specimens is not even close to the spectacular wild fish. If you can find wild specimens they are well worth it.

Lake Wanam has been the subject of a management project co-ordinated by famous aquarist Heiko Bleher, who became concerned by an apparent drop in numbers of both this species and the barred rainbowfish (Chilatherina fasciata), which is also found in the lake. The drop in numbers is thought to be a result of the introduction of non-native Tilapia, Gambusia and carp species into the lake, along with a significant increase in the number of humans living in the area. G. wanamensis is now considered ...

This species was originally classified in the genus Limnochromis. There are a couple of colour morphs available and these should not be mixed in aquaria, as they may hybridise. In nature, this fish feeds in a similar way to Geophagus species, in that it will sift sand through its gills to extract invertebrates hidden in the substrate. It is a deep water fish and has been recorded foraging at depths of up to 200 metres. These movements seem to be related to the presence of the plankton on which...

Also known as Peter's elephantnose, this fascinating species is currently the most common Mormyrid in the hobby. Sadly, its popularity means it is often kept in unsuitable conditions. To deny the fish a soft substrate really is cruel, as it uses its "trunk" to locate food hidden in the substrate. It also needs dim lighting, and will commonly become withdrawn and pine away if kept under bright lights. If you cannot provide suitable lighting, add food to the tank at lights out to al...

This fish is also commonly sold as the dragon or Peruvian goby, or dragon fish, and its bizarre appearance has made it popular in the trade. This is unfortunate, as not only does it grow very large, but it has specialised feeding requirements and does not survive for very long in freshwater. When provided with the correct conditions, however, it makes a unique and fascinating captive subject. There is a smaller species in the genus, G. peruanus, that does survive in freshwater, being a riverine ...

G. niloticus is the only species in its genus and is utterly unique. Unlike other knifefish it has an extended dorsal rather thangiving rise to the alternative common name of upside-down knifefish. Despite this common name, it is actually more closely related to the Mormyrid group of species. It is a truly beautiful sight in motion despite its lack of bright colours, as it can move in virtually any direction with ease using its undulatingto 'steer'. It also produces a weak electrical d...

G. filamentosa has appeared in the ornamental trade but is evidently delicate and therefore recommended only to experienced aquarists. It can be told apart from congeners by the following combination of characters: possession of filamentous dorsal and anal-fin rays in males; body transparent to translucent yellowish-brown colour in life; absence of a highly-extended second anal-fin spine; absence of carmine-red pigmentation in the dorsal, anal an...

A densely-planted tank with floating vegetation and roots, twigs or branches and natural leaf litter would seem appropriate. There's no need to use natural peat, the collection of which is both unsustainable and environmentally-destructive. Filtration should not be strong with an air-powered sponge-type unit ideal, and given it naturally inhab...

Not often seen in the hobby, probably because it's a fairly bland species when mature. Juveniles are more attractive, possessing reddish unpaired fins, but these fade as the fish mature. It is, however, both peaceful and hardy and is a good choice for the beginner. It is sometimes seen labelled as G. socolofi. This name is now considered a junior synonym of G. bondi....

This species is ubiquitous in most dealers' tanks and is one of the best choices for the newcomer to fishkeeping. All the fish sold in the trade have been captive bred and as such are unfussy regarding water chemistry and diet. The intense black colouration of juveniles does fade as they grow, but adult fish provide a subtle contrast to most other commonly kept species. It goes by several common names, including 'butterfly tetra', 'black skirt tetra' and simply '...

A very interesting species that sadly is only recommended to the specialist able to provide it with the specific conditions it requires for its long term health. There are a couple of different colour forms available, dependant on locality.

Following Roberts (1997) G. ariza can be diagnosed by the following combination of characters: body with variably intense thin stripes dustributed mostly above the lateral line; larger individuals sometimes with a broad midlateral stripe; 32-35 lateral scales; 7-8/1/5-6 transverse scale rows; 8-9 branched dorsal-fin rays 8-9; 22-24+ 11-12=34(4), 35 (3) vertebrae; live colour pattern variable, overall dull dirty white to greyish, silvery or yellow.

Recorded from the middle to lower Mekong river basin in southern China (Yiunnan province), Laos, Thailand, and Cambodia, plus the Chao Phraya watershed in central Thailand. Type locality is 'Thailand: Lam Ton Lang, a tributary of Menam Sak [Mae Nam Pa Sak; Ban Lam Thong Lang, village northwest of Pakjong'.

G. lobatus can be distinguished from congeners by the following combination of characters: possession of 32-33 + 2-3 lateral line scales; 5½ scale rows between lateral line and base of dorsal-fin; body relatively slender, depth fits 3.7-4.0 times in SL; snout often projecting strongly; body plain silver in colour.

G. ornatapinnis can be distinguished from congeners by the following combination of characters: head small; snout relatively short and blunt; caudal peduncle very deep; pectoral, pelvic, and anal fins usually reddish-orange or rose-tinted; pelvic and anal fins often with white tips; barbels completely absent.

G. siamensis can be distinguished from congeners by the following combination of characters: possession of 5½ lateral line scales; body relatively deep, depth fits 3.2-3.4 times in SL; head large and broad, width fits 5.5-6.7 times in SL; snout not or only weakly projecting; body plain silver in colour with no dark marking on caudal peduncle.

Gymnothorax tile

Not a good beginner's species, due to its very respectable adult size, but it makes a stunning oddball addition to communities of larger fish. It's sensitive to many aquarium medications, particularly those containing copper. The genus Gymnotus has undergone considerable taxonomic revision in recent years, with over 20 new species being described since 1994, including several that were originally considered to be G. carapo. The systematics of the genus are still not fully understood...

The genus Gymnotus has undergone considerable taxonomic revision in recent years, with over 20 new species being described since 1994, of which this stunning species is one. It's still very rare in the hobby and tends to command a high price when available. Like other Gymnotids, it produces a weak electric field using specially-adapted muscle tissue located towards the tail. It also possesses electroreceptors which allow the fish to receive electrical signals. With these the fish can sense ...