Songkhram

The emerald betta, Betta smaragdina, is a bubble-nesting labyrinth fish from the Khorat Plateau in eastern Thailand and Mekong tributaries in Laos. It inhabits still and sluggish waters such as rice paddies, swamps and roadside ditches. It has been line-bred for aggression in eastern Thailand, and selectively bred and hybridised for the ornamental trade into colour forms that do not occur naturally. Wild populations vary in the extent of red or green patterning and are often labelled by locality.

Oryzias songkhramensis is a small ricefish known only from the Songkhram River basin in northeastern Thailand and the Mekong drainage in Laos. It lives only in fresh, normally standing water such as shallow pools, ditches, rice paddies and clear water swamps. Males have black and yellow or orange marginal bands on the caudal-fin lobes, and there is a black spot at the base of the pectoral fins. It resembles O. mekongensis, which has been available in the hobby.

The sparkling gourami, Trichopsis pumila, is a small labyrinth fish from the lower Mekong basin and central and southern Thailand. Also known as the pygmy gourami, it has a solid dark midlateral stripe topped by a row of dark blotches, which with its small size separates it from T. schalleri. Both sexes produce audible 'croaking' sounds with a specialised pectoral mechanism, and most traded fish are produced commercially.

The redtail loach, Yasuhikotakia modesta, is a botiid loach from the middle and lower Mekong and the Chao Phraya and Mae Klong drainages of Thailand. One of the more commonly encountered botiids in the hobby, it is also sold as 'blue', 'orange-finned' or 'red-finned' botia. Some fish are dyed and sold as 'blueberry' or 'raspberry' loach, and their health is normally compromised by the process. Deeper-bodied than the similar Y. lecontei, it grows to 250 mm and needs an aquarium with a base of at least 150 ∗ 45 cm.

The royal featherback, Chitala blanci, is a very large notopterid endemic to the Mekong drainage in Laos, Thailand, Vietnam and Cambodia. Also sold as the 'royal knifefish', it reaches 1200 mm SL and arguably has no place in the ornamental hobby, being suitable only for public installations or the very largest private aquaria. Many small dark spots on the front of the body merge into oblique stripes, and it is thought to be threatened by dam construction.

Mystacoleucus atridorsalis is a pelagic cyprinid considered endemic to the lower Mekong basin in Laos, Thailand and Cambodia. It favours flowing lowland river channels and moves into flooded forest during the wet season. A triangular blotch at the tip of the dorsal fin helps separate it from congeners, and like all Mystacoleucus it has a forward-pointing predorsal spine that can become entangled in an aquarium net.

Mystacoleucus ectypus is a pelagic cyprinid from the middle Mekong basin in Laos and Thailand, and may be endemic to the Khorat Plateau. It inhabits flowing lowland rivers and swift tributary streams with rock and gravel. It has a triangular blotch at the tip of the dorsal fin but no black fin margins or crescent-shaped scale markings, and like all Mystacoleucus it has a forward-pointing predorsal spine that can snag in a net.