Oryzias wolasi · Wolasi Ricefish

Overview

Oryzias wolasi: Its relatively deep, golden body develops a darker purple cast in courting males. Similar blue-sheened ricefishes can be confused in trade, making locality information useful.

Distribution & habitat

Four known localities south of Kendari in Southeast Sulawesi, Indonesia, include the Wolasi and Andambao rivers, waterfalls, and a spring-fed coastal stream. Karst habitats range from flowing water to persistent pools left in a nearly dry seasonal channel.

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

Use appropriately small foods, combining quality crushed flakes or fine granules with microworms and Artemia nauplii. Surface grazing has been observed in adults, suggesting but not confirming an algal component in the natural diet.

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 are slimmer and more colorful, with longer dorsal and anal fins and a short, slightly conical genital tube. Females have a bilobed papilla and orange olfactory tissue.

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

Earlier labels include Kendari, neon, and Sulawesi. Compared with Oryzias woworae, it has a deeper body and thicker tail base, with darker purple nuptial coloration. Avoid mixing similar forms for breeding.