Oryzias songkhramensis

Overview

Oryzias songkhramensis: A small, generally peaceful ricefish, it has a dark pectoral-base spot and males develop black and yellow-orange bands along the tail lobes.

Distribution & habitat

Known sites lie in northeastern Thailand’s Songkhram basin and parts of the middle Mekong drainage in Laos. Shallow pools, ditches, paddies, and clear freshwater swamps provide still water over sand, mud, and organic debris.

Aquarium setup

Combine dark substrate, thick planting, roots, wood, and floating cover with open swimming space.Sparse surroundings can reduce display color, whereas dense growth also shelters young fish.

Diet & feeding

Wild prey includes small insects, worms, crustaceans, and other zooplankton. Suitably sized dry food is accepted, supplemented daily with small live or frozen items such as Daphnia, Artemia, and chopped bloodworms.

Behaviour & compatibility

Eight or more individuals form a more confident group. Choose similarly small, peaceful companions; suitable freshwater shrimp are also possible. Courting males may defend brief territories despite an otherwise gentle disposition. Use a dedicated group for breeding and avoid other ricefish species because of hybridization risk.

Sexual dimorphism

Males have stronger tail bands, a convex anal-fin edge, and extended leading dorsal and anal rays. Females have fainter markings, a slightly concave anal margin, and longer pelvic rays. The male genital papilla is tubular; the female’s is bilobed.

Breeding

Well-conditioned females can produce eggs every few days or even daily. Spawning generally takes place early in the morning as males darken and defend small temporary spaces. Adhesive eggs are released and fertilized together. They remain attached beneath the female temporarily, then are transferred singly or in small clusters to plants or other media. Fine vegetation and spawning mops are suitable.

Incubation usually lasts one to three weeks, depending on temperature. Adults commonly ignore eggs but eat free-swimming fry. Transfer eggs or young to a nursery filled with parental-tank water, or provide dense cover for some to survive in place. Microworms and Artemia nauplii are accepted after free swimming begins. Separate markedly different sizes of juveniles to prevent the larger ones eating the smaller.

Notes

The similar Oryzias mekongensis has appeared in trade, so general ricefish appearance alone cannot establish identity.