A typical companion fish of harlequin barbs (Trigonostigma), chocolate gouramis (Sphaerichthys) and other blackwater fish is Rasbora einthovenii. The species is unfortunately very rarely imported, although it has a large range. It is found on the large Sunda islands of Sumatra and Borneo, on the Malay Peninsula and in southern Thailand in suitable biotopes. Usually it is found in moderately flowing, small streams, which are only a few meters wide and 1-2 meters deep.
At first sight R. einhovenii resembles the ubiquitous longitudinal striped rasboras of Southeast Asia (Rasbora paviana and related species), but a closer look reveals the species-typical characteristics: the somewhat stocky build with the relatively blunt head profile, the fact that the longitudinal black stripe runs through the middle of the caudal fin (this ends at the base of the caudal fin in all other longitudinal striped rasboras), and the delicate blue and pink longitudinal stripes above the prominent black band.
Rasbora einthovenii usually reaches a length of 5-6 cm, but can grow up to 9 cm in exceptional cases. It is a perfect community fish for well planted aquariums with dark substrate and peaceful fish, such as labyrinths, barbs, etc. They are typical free spawners, caring for spawn and juveniles only insofar as they see them as a change from their usual diet. External sex differences are only weakly pronounced, males are slightly smaller and more delicate than females.
For our customers: the fish have code 451902 on our stock list. Please note that we supply exclusively to wholesalers.
From Thailand we just received once again the dwarfish brilliant redfin rasbora, Rasbora rubrodorsalis. This species was recognized as a distinct species only late, in 1997, although it is widely distributed in Southeast Asia (Laos, Cambodia, Thailand, Vietnam). It was formerly thought to be a juvenile form of the similar species Rasbora borapetensis. Unlike R. borapetensis, R. rubrodorsalis has a red spot in the dorsal fin and remains much smaller with a maximum standard length of 3 cm (not including the caudal fin). R. borapetensis grows twice as large to 6 cm standard length.
Rasbora rubrodorsalis is an excellent schooling fish for planted aquariums with Southeast Asian character. This extremely peaceful species is very adaptable. In nature the water temperatures vary seasonally in the range of below 20°C (November to February) and above 30°C (March to October). There are also no special requirements regarding the water values. Females become sexually mature at about 2 cm in length. Males are generally somewhat smaller and more delicate. In the wild, these animals are short-lived and reproduce year-round. In a scientific study that intensively studied these fishlets in Laos for a year, the oldest specimen found in the wild was 121 days old (a female), the oldest male was 92 days old, and sexual maturity sets in at around 50 days of age. In the aquarium, however, the fish grow much older, 2-3 years.
For our customers: the animals have code 452862 on our stock list. Please note that we supply only wholesale.
The Dwarf rasbora (Boraras maculatus, formerly known as Rasbora maculata) is the species of genus Boraras that is known for the longest time in the hobby. None of these species grows bigger than 2-3 cm and thus they are perfect candidates for the so-called nano-aquaria. All like to be kept in soft and acidic water, rather dark tanks, that should nevertheless be well planted (best use swimming plants), fine live food (although they also take readily dried food) and company of their own kind.
The Dwarf rasbora inhabits the malayian peninsula, southern Thailand and Sumatra. Initially it was often thought to represent the juvenile of the much larger growing species Rasbora kalochroma, but observations of the fish in aquaria and their successful breeding left no doubt on the validity of the species.
There do exist lots of varieties of the Dwarf rasbora which may proof to be different species one day. Typical for all of them is the large shoulder spot, which is in any cases bigger than the eye. The ground coloration of the body depends on the variety and can be light orange up to deep red. Some populations have an additional black spot (all Dwarf rasboras have three black blotches: one on the shoulder, one on the origin of the anal fin, and one on the caudal fin base) on the beginning of the caudal peduncle right above the anal fin.
Our animals currently in the stock, of which the photos for this post were also taken, come from Indonesia.
For our customers: the species has code 452702 on our stocklist. Please note that we exclusively supply to the wholesale market.
One of the unfortunately very rare black water rasboras on offer is Rasbora cephalotaenia. The species is quite widespread on the Malay Peninsula to southern Thailand and on the large Sunda Islands (Borneo, Sumatra), presumably it is also found on smaller islands of the Sunda archipelago in suitable habitats. However, as peat swamps are drained all over South East Asia and used for oil palm plantations, this beautiful species is also endangered by environmental destruction.
As far as the water composition is concerned, Rasbora cephalotaenia are undemanding in themselves, at least as long as one does not want to breed; however, the beautiful colour marks, which are needed in the dark black water (practically no hardness, pH between 4 and 5) due to the poor underwater visibility to identify conspecifics, shine considerably more intensely in soft water tinted brownish by peat, dead leaves and alder cones.
Rasbora cephalotaenia grows to over 10 cm in length and is ideal for community aquariums, e.g. with harlequin barbs, labyrinths or catfish, given they are also blackwater inhabitants. The peaceful animals like to swim in a swarm with their conspecifics. They are free spawners without brood care. They eat all usual fish food. The water temperature should be between 24 and 28°C, for breeding 2-3°C higher.
For our customers: the fish have code 451602 on our stocklist. Please note that we only supply the wholesale trade.
In the black water of Sundaland (Indonesia, Malay Peninsula) you will find many wonderful aquarium fish like chocolate gouramis, harlequin barbs and kuhli loaches. However, these are only the best known; the numerous species of small and colourful barbs and rasboras, for example, are only known by a few.
Among them is Trigonopoma pauciperforatum (formerly Rasbora pauciperforata), which we have once again received from Indonesia, one of the prettiest. In fact, the fish, usually up to 4 cm long (some literature say up to 7 cm), looks like a twin species of the glow-light tetra (Hemigrammus erythrozonus) from the Essequibo River in Guyana, although the muzzle of T. pauciperforatum is much more pointed and the adipose fin is missing.
For our customers: the animals have code 452602 on our stocklist. Please note that we only supply wholesalers.
As early as 1914 the then very prominent German aquarist J. P. Arnold illustrated a new species of Rasbora in a German aquarium magazine, imported by the company Scholze & Pötzsche and said to originate from Sumatra. In 1922 E. Ahl from Berlin Museum described this species scientifically as Rasbora urophthalma and since these days this charming dwarf rasbora is known as R. urophthalma (common name: Least rasbora) in the aquarium hobby. In 1991 M. Kottelat found when re-examining Ahl´s specimens in Berlin Museum that they were not identical with what is well known in the hobby. Thus the name Rasbora urophthalma was not available anymore for the Least rasbora and Kottelat gave a new name on them: Rasbora urophthalmoides. He also stated that the Least rasbora is not known from Indonesia.
Today the scientific name for the Least rasbora is Boraras urophthalmoides. It is known from Thailand, Cambodia, and Vietnam. For the aquarium hobby, it is imported mainly from the latter country.
Like all dwarf rasboras this species is best kept in small aquaria in a one-species tank. The water should be soft and acidic. Due to it´s origin for regular keeping temperatures of 20-22°C are enough, but for breeding the temperature should be raised to 26-28°C.
For our customers: the species has code 453001 on our stocklist. Please note that we exclusively supply to the wholesale market.
One of the undoubtedly most beautiful Rasbora species is R. kalochroma – and one of the most sensitive. They are typical black water fish which react very sensitively during the acclimatisation phase to increased bacteria contamination, which occurs almost inevitably in “normal” water. When we were now offered 1-2 cm long youngsters, we took advantage, because young fish are basically much more adaptable than adult animals. And the plan worked out! We now have very beautiful, well adapted Rasbora kalochroma in our stock.
The colouring of the fish in the photos is only a drab copy of the colouring they show in well equipped black water tanks; unfortunately you cannot photograph in such water or the colours would appear completely unnatural. In the past, R. kalochroma was considered to be the adult form of the dwarf rasbora (Boraras maculatus); however, the similarity is not very great from today’s point of view (see https://www.aquariumglaser.de/fischarchiv/boraras_maculatus_en/). Rasbora kalochroma becomes about 8-10 cm long and is a peaceful fish that appreciates the company of conspecifics.
For our customers: the animals have code 452300 on our stocklist. Please note that we only supply wholesalers.
We could import this pretty fish finally once more via Singapore. The two species of the genus Trigonopoma were placed in the genus Rasbora for a very long time. The second species, T. pauciperforata, the glowlight rasbora, occurs interestingly very often syntopically with its close relative.
In the elder aquarium literature Trigonopoma gracile was usually named Rasbora taeniata. The first importation to Germany was as early as 1913; at that time is was not yet known to science yet. Persons interested in the history of the species and the different names should study the paper of Zarske in the Aquaristik Fachmagzin 213 (June/July 2010), which can be downloaded for free from Dr Axel Zarskes homepage at Senckenberg Museum. Sadly it is available in German only.
The pretty rasbora attains a maximum length of about 5 cm. In the natural habitat it can be found along with fish like harlequin rasboras (Trigonostigma heteromorpha) or chocolate gouramis (Sphaerichthys osphronemoides). The rasbora is a perfect community fish for tanks with soft and acidic water, a dark bottom (place some peat on it) and delicate water plants.
For our customers: the fish have code 452002 on our stocklist. Please note that we exclusively supply the wholesale trade.
The slender rasbora (Rasbora daniconius) inhabits a very large area in Southeast Asia. From the Malaian peninsula to the Mekong and the Indus it occurs in the a variety of habitats: channels, ponds, flooded (rice) fields and slowly flowing rivers. Due to the enormous area and the adjustment to different water types it can be assumed that R. daniconius does not place excessive requirements for the life in the aquarium. As long as one avoids extreme conditions slender rasboras will do fine. For this is to an overall length of 15 cm growing fish, the tank should not be too small (1 m), the fish need space being very active swimmers. With varied feeding and regular partial water changes this undemanding species is an almost ideal fish for beginners.
For our customers: the fish have code 451703 on our stocklist. Please note that we exclusivelky supply the wholesale trade.
Photo F. Schäfer, Text K. Diehl