#rainbowfishes

Sisters to such 'true' rainbowfishes are a number of related silversides, including the members of the genus Pseudomugil, or the blue-eyes, that are native to Australia and New Guinea. Although the honey blue-eye (P. mellis) is rare in the wild, and ranked as endangered, captive bred stock may be sourced. This species is so named for it's coloration blue eyes are small fishes, and P. mellis grows yo between 2.5 and sometimes 4 centimeters long, or between 1 and 1 and a 1/2 inches. Naturally they are found in large schools of conspecifics.

The habitats of P. mellis are freshwater swamps, dune lakes, and slow flowing creeks amid the sandy coastal heathlands of subtropical eastern Australia. These environments are characterized by a sand or mud bottom, rich vegetation of reeds or water lilies, and usually although not always, their water is stained by tannins. The pH of such water is below neutral, and can be as low as pH 4.4. in subtropical latitudes the temperature is seasonal, but the upper temperatures do not exceed 27-32 degrees centigrade. P. mellis is sympatric in it's habitats with such fishes as ornate rainbowfish (Rhadinocentrus ornatus), crimson-spotted rainbowfish (Melanotaenia duboulayi), empire gudgeon or goby (Hypselrotris compressa), and Oxleyan pygmy perch (Nannoperca oxleyana). They are sometimes sympatric with another blue-eye species (P. signifer) on Fraser Island, and in the Schnapper and Big Tuan Creeks on the mainland

B. madagascariensis are known from rivers and lakes between the Ivoloina and the Manambolo rivers. Following their translocation to marshes near Antananarivo, the species has become established in the Betsiboka basin. This species inhabits clear, shaded streams, preferring slow-flowing sections.

Shade from an overhanging forest canopy, is demonstrably an important habitat requirement for these fish in the wild, and they depend on arthropods from the canopy overhead as their natural food. Without shading from above they are also more vulnerable to predatory birds that hunt fish. Adult B. madagascariensis inhabit deeper water than do the younger fishes.

B. madagascariensis is often confused with a more southern and upland species, B. geayi, that is only known from the Mananjary drainage in the south of Madagascar. There it can be found in small streams, between 300 and 600 meters above sea level. Most of the rainbowfish traded as B. geayi are more accurately B. madagascariensis, and there are some anatomical differences between these two related species.

Rainbowfish are a freshwater subclade of silversides, distributed in the nowadays well separated regions of Madagascar and Australasia. This is a difficult distribution to explain, other than to note that the Madagascan and Australasian rainbowfishes are only distantly related, though together comprise an ancient clade. Their kinship among the other silversides is revealed by similarities of behaviors, and physical sexual dimorphism, among other characteristics.

It is thus assumed that ancient, ancestral rainbowfishes had lived on both continents, prior to the breakup of Gondwana into island fragments. If this is correct, then rainbowfishes related to Bedotia must once have lived in India, of which Madagascar was once a part. Freshwater organisms cannot cross oceans, so like land animals, their distributions and relationships predict continental drift.

B. madagascariensis are a rainbowfish that can usually be kept without problems, and can be recommended for beginners. Regarding the chemical parameters of aquarium water, and the matter of food, these pretty fishes are rather undemanding. These are schooling fishes, and they need to be maintained together in some numbers. Yet the presence of too many males in the group will create conflicts and distress.

Though Bedotia sp. are not very large fishes they are active, and their aquarium must allow them good, unobstructed swimming space, but also opportunity to retreat. Without which these fish are less likely to 'color up'. Dense planting in part of the aquarium allows this, and gives the females somewhere to scatter their eggs. Bedotia sp. have mouths large enough for small fish to be eaten. Thus it is advised that their tankmates be relatively large in proportion to the rainbowfishes.

Madagascar rainbowfishes are easy to feed on defrosted food of suitable nature, and they will also consume proprietary flake preparations. For these fishes, flakes are quite apt because they float at the water surface. Despite claims circulated in the popular aquarium literature, fish from the eastern flowing drainages of Madagascar, are in fact inhabitants of soft water with a low pH. They are not native to hard or strongly alkaline waters.

On Madagascar this species is recorded even in waters with a pH slightly below 5. But people actually are keeping them in water that is more neutral and even a bit alkaline, such as a pH of 7.5. It is sometimes repeated that Madagascan rainbowfishes like a temperature of 20 to 24 degrees centigrade.

B. madagascariensis are lowland fish found only at altitudes below 30 meters, and in the wild, the water temperature they experience can reportedly range from 23 to 32 degrees, within the period of one month. More recently, information based on zookeeping has indicated and standardized their care, at a temperature of 24 to 25 degrees centigrade.

M. splendida display a preference for vegetated freshwater habitats, and an aversion to brackish conditions. However they have otherwise broad habitat preferences, including slow flowing rivers and stream environments, swamps, and lagoons. This broad diversity of habitats is responsible for a good degree of variation, among the populations of M. splendida This species is known to migrate in the wet season, when the land is inundated, and which is also their season of spawning condition.

Like some other animal species, which include humans, M. splendida possesses a number of geographical races or subspecies. Subspecies are 'fuzzy' subcategories within a broader species rank taxon - and the matter of species itself, can be quite an arbitrary and subjective affair to begin with. Regardless the state of knowledge, such categories are demarcated on time and space, only in the minds of human observers.

The rainbowfishes can be variable, and the pigments and color patterns of M. splendida can vary, not only between, but also within its populations. Coloration and even body shape in M. splendida, are subject to the effects of their ambient habitats. It helps more to know the source of the fish, rather than identify the subspecies. Male M. splendida have a deeper body than fo the females.

Outside of Australia herself, the freshwater fishes of Australasian are relatively under-represented in the aquarium trade. Of all the Australian and nearby New Guinean endemic fishes, the most familiar to aquarists are surely the stunning rainbowfishes. A clade which are, by now, much too familiar to be 'oddballs', although they are not quite as ubiquitous as the characins, loaches, carps, catfish, cichlids, or gouramis from other continents.

Other than a few genera of freshwater catfishes, Australasia natively lacks a major fish clade called the ostariophysians. This ubiquitous clade is dominant in continental freshwaters elsewhere. Rainbowfishes are technically silversides, that succeed by having radiated into the kinds of freshwater niches, that are occupied by other fish clades outside Australasia. Like the Antipodean marsupials, rainbowfishes are an integral part of the weird and wonderful Australian fauna.

For some reason, aquarists exaggerate the heat tolerance of this species. Yes, they do tolerate high temperatures, which is an adaptation to seasonality in their range in the wild. But they should not be exposed to temperatures as high as the mid 30s in degrees centigrade. It has been suggested that a constant 28 degrees centigrade may be optimal for this species, and it normally experiences water temperatures of about 23 to 30 degrees centigrade, with some months being warmer than the others.

I have seen records of this fish at a locality where the dry season temperature, was between 21 and 22 degrees, and the pH was close to 6.5. As might be expected, M. splendida is reasonably tolerant when it comes to pH, however a supposed range of pH tolerance from 4.5 to 8.5, is surely far broader than the optimum range. It seems that a circumneutral pH is most likely to be optimal.

As with other rainbowfishes, M. splrndida is a peaceful and gregarious species, one that must be accommodated in groups of at least eight, and one that is ideal for community aquariums. M. splendida are harmless to growing plants, and life in a planted aquarium encourages them to be less nervous. In the wild, their environment also includes such debris as submerged wood. Like the other rainbowfishes of similar size, M. splendida ample swimming space. M. splendida are insectivores, preferring to feed from the surface, and they will consume various, appropriate defrosted and dried preparations.