Papua New Guinea

This species is not traded for aquaria but is occasionally exported as bycatch among shipments of other species. It differs from congeners in that the outermost row of teeth are not enlarged plus the interorbital space and cheek below eye are not scaled. Butis spp. are largely nocturnal ambush predators with cryptic...

Butis spp. are largely nocturnal ambush predators with cryptic patterning to help them blend in with their surroundings. They can also lighten and darken their body colouration to an extent, have a habit of aligning themselves with solid surfaces whether horizontal, vertical, or inverted, and often swim in an upside-down position. The genus is usually included in the family Eleotridae of which members are often referred to...

Apparently restricted to the southern portion of New Guinea, between the Lorentz River in Papua province, Indonesia, and Kikori River in Gulf province, Papua New Guinea. The majority of records pertain to the lower Fly River basin in Western province, southwestern Papua New Guinea.

Occurs in northern and eastern Australia and southern New Guinea. In the former its range extends from the Pilbara and Kimberley regions of Western Australia state around the northern and eastern coastlines of the continent as far as the Towamba river system in New South Wales state.

There also exists a sister-group relationship between the Melanotaeniidae and Malagasy family Bedotiidae, which may seem surprising given their respective modern-day distributional patterns. The precise origin and subsequent dispersal of the two families has been the subject of debate, with some palentologists suggesting that Madagascar's freshwater fishes derived froma trans-oceanic dispersal during the Cenozoic Era, but the most compelling arguments currently indicate a freshwater radiation which occurred during the Mezozoic break-up of Gondwana.

Type locality is ‘Nicol Bay, Cape York, Queensland, Australia’, and this species is restricted to the tips of northern Australia and southern Papua New Guinea. In Australia records exist only from the Jardine and Jackson river systems on the Cape York Peninsula, while in Papua New Guinea it’s known from the Fly River plus some other drainages.

Euryhaline and thus capable of withstanding significant fluctuations in salinity and other water conditions. It's been recorded in full marine conditions as well as pure freshwater environments, and commonly inhabits coastal mangrove creeks and swamps. Such changes may occur on a daily or seasonal basis depending on locality, with some habitats influenced by daily tides whereas others become hypersal...

This species is also traded as 'forktail rainbowfish' or 'yellow forktail', and it's also undergone several changes in scientific name since description. Pseudomugil furcatus is the original designation, but Allen (1980) created the genus Popondetta for it on the basis of morphological characters including number of anal-fin rays (16-20 in P. furcatus, 8-12 in other Pseudomugil spp.), absence of anterior...

Described from 'Rivulet in sago forest at Ngaiguli, Terangan, Aru Island, Aru Islands, Maluku, Indonesia', corresponding to the island now normally referred to as 'Trangan' in the Aru Islands group, eastern Indonesia. The islands are located in the Arafura Sea, with western New Guinea to the north and the Arnhem Land Region of Australia's Northern Territory to the south, and though they lie within Maluku province of eastern Indonesia, are part of the Australian continent in a geological sense.

Euryhaline and mostly inhabits coastal floodplains where it's found in both fresh and brackish habitats, including tidal estuaries and salt marshes. It's particularly common in swamps, billabongs, and slow-moving streams where aquatic vegetation grows densely, but some populations have colonised upper sections of freshwater streams. Larger individuals may also move into main river channels. Tappin (2010) gives the following ranges of parameters based on those taken from various localities: temperature 27 - 38 °C, pH 5...

The fused pelvic fins form a structure normally referred to as the 'pelvic disc', a common feature among gobiids which is used to adhere to rocks and other submerged surfaces. In Sicyopus, as in Stiphodon, this is short-based and attached to the belly only between the fifth pair of fin rays whereas in other sicydiines it's attached between all five rays (Watson, 2005).

Type locality is given as 'Boleling, northern Bali, Indonesia' which appears to correspond to modern-day Buleleng, but this species is currently understood to have a patchy but wide distribution with a range stretching westwards from the Marquesas Islands (French Polynesia), throughout much of Vanuatu, New Caledonia, the Solomon Islands, Papua New Guinea, Palau, Fiji, Indonesia, the Philippines, Japan, Taiwan, and most recently, southern mainland China...

Type locality is given as 'Stream at end of long narrow bay, Waigeo Island, Irian Jaya, Indonesia', with the species also known from rivers draining the northern slope of New Guinea as well as Halmahera Island (Indonesia), the Admiralty Islands (Papua New Guinea), the Bismarck Archipelago (Papua New Guinea), D'Entrecasteaux Islands (Papua New Guinea), Louisiade Archipelago (Papua New Guinea), Bougainville (Papua New Guinea), Vanuatu, and...

This species probably hasn't been seen in the trade yet but should make an interesting aquarium fish if it ever becomes available. Within the genus it's most similar to S. surrufus and S. mele from which it differs only in terms of meristics. In description it's distinguished from the former only by possession of more teeth in the upper jaw although images of live specimens depict S. surrufus as a more intensely-coloured, reddish fi...

This species is not traded commercially at present and the specimen pictured above was brought back from northern Papua New Guinea by private collectors in 2008. It's diagnosable from other members in the genus by possession of 10 segmented rays in the second dorsal fin, males with filamentous spines in the firstandusually with 14 rays. Colour patterning in males is also distinctive (see 'Sexual Dimorphism'). The Gobiidae is the most speciose vert...

This species has been traded for a number of years, though not always under the correct name. We've seen it on sale as S. elegans or S. atropurpureus on numerous occasions, for example, and other trade names include 'Sumatran blue neon goby', 'cobalt blue goby' and 'freshwater neon goby'. Further confusion has arisen because other species are sometimes sold as S. semoni meaning identification has not always been easy and there ...

Wild swordtails are a fairly basic green colur. However the vast majority of swordtails available in the hobby today are hybrids of X.helleri with X.maculatus or X.variatus. There are a huge number of selectively-bred varieties available, including wagtail, lyretail, tuxedo, albino, neon, red, green and hi-fin. Swordtails may undergo what appears to be a change in sex. In young fish this may simply be late development. However some adult females develop male characteristics which is thought ...