Order Beloniformes
Family Adrianichthyidae
Subfamily ( Oryziinae )
Genus Oryzias.
Distributed in Southeast Asia, particularly in Japan, India, the Malay Peninsula, Java, Sulawesi, and Sri Lanka. They differ from killifishes by a long anal fin and a non-proractile upper jaw. At least 20 species are known, so similar to each other that identifying the specific species is only possible for specialists. These are small fish (2-5 cm) living in warm, shallow water bodies densely overgrown with plants. (Oryza in Latin means “rice”). Their body is more or less elongated, laterally compressed, with pectoral fins positioned relatively high. The head and front of the back are flattened. The body is semi-transparent, elongated, compressed laterally. The head is flattened from above. The dorsal fin is small, set back.
The coloration of Oryzias fish is yellowish or grayish-green. Males are smaller and more slender than females, differing in pointed fin tips. Peaceful, schooling fish. They stay in schools near the water surface. Oryzias are kept in small groups in relatively small aquariums, preferably with a large water surface area, planted with plants, and with free swimming space. Alone, the fish quickly die or join some group (e.g., Danios, Atherinids). Aeration, filtration, and regular water changes are necessary. They accept any live and dry food. The fish are undemanding regarding the chemical composition of water, temperature 20-25°C. dH 5-15°, pH 6.0-7.5.
These fish are exceptionally interesting in terms of their reproductive biology. They mature at 4-6 months. For breeding, 12-15 liter aquariums with plants floating on the surface are usually used. The water is soft, preferably peat-treated. Reproduction in a general aquarium is also possible. Spawning occurs after vigorous courtship by the male towards the female. The eggs (from 12 to 35 pieces up to 225–255 in Oryzias latipes), connected by thin threads, hang in the form of a grape cluster near the female’s genital opening. After a few hours or days, she shakes them off onto the plants. The female attaches the eggs to plants, where they hang for 3-10 days, and sometimes two weeks, after which fry hatch from the eggs and can immediately feed on infusoria. In captivity, they live up to 3 years.
— Oryzias celebensis [Weber, 1894] — Celebes Medaka. Synonym: Haplochilus celebensis. (Eng. Celebes Medaka). Indonesia, Sulawesi. 4 cm. Body delicate green, semi-transparent, dorsal fin is located in the rear part. A thin dark brown to black longitudinal lateral line begins from the middle of the body to the caudal peduncle. Pelvic fins are relatively small, usually with six rays. Caudal fin with yellow to orange lobes at the edges. Fins are colorless, with an iridescent sheen along the edge of the anal and dorsal fins. In males, the dorsal and anal fins are larger than in females.
Schooling fish. They stay mainly near the water surface, where some floating plants still leave a little free space for the fish to swim. It is recommended to keep them together with fish of approximately the same size swimming in the lower and middle zones of the aquarium. Males can be aggressive, defending their territory.
Oryzias feel good in a gentle current, with fine-leaved vegetation and sunny aquarium lighting. Adult fish prefer water fleas, cyclops, and corethra swimming in the water column. Breeding is successful, but raising the fry is not easy at all. Fertilization is external. Females glue fertilized eggs to their belly. The eggs fall off as the female brushes her belly against the plants. T 23-26°C; pH 7.0-8.5; dH 10-15°.
— Oryzias dancena [Hamilton, 1822] — Indian Ricefish. Synonym: Cyprinus dancena, Aplocheilus mcclellandi. (Eng. Indian Ricefish, Blue Eye Rice). India, Bangladesh, Myanmar, Sri Lanka, in brackish and fresh water. 3 cm. Adult males are slightly more slender and have elongated, thread-like rays in the dorsal and anal fins, some of them with a white edge. The anal fin is convex with extended ray tips in males, straight or slightly concave in females. They have a truncated, rather than crescent-shaped or emarginate, caudal fin, which distinguishes them from relatives.
Keep in a large school aquarium with dense fine vegetation and floating plants with long roots, among which fry hide. Dwarf shrimp, as well as fish of approximately the same size and not too disturbing, are suitable companions. Slightly acidic environment in the medium-hard water range is suitable; they can live in brackish water. Males constantly court females. Females carry eggs on their belly, the eggs fall off as the female brushes her belly against plants. Sorting fry of different ages is necessary, as older ones can eat smaller ones. Feed with live and dry food of appropriate size. pH 7.0-8.5; T 23-27°C.
— Oryzias matanensis [Aurich, 1935] — Matana Ricefish. Synonym: Aplocheilus matanensis. Sulawesi Island (Celebes). 5 cm. Beige-green with a bright yellow-orange border along the dorsal, anal fins, and tail lobes. Delicate species. Peaceful schooling, active, timid fish, staying in the upper water layer. Better kept in a species aquarium with occasional thickets. Undemanding to the chemical composition of water.
— Oryzias minutillus [Smith, 1945] — Dwarf Ricefish. (Eng. Dwarf Ricefish, Dwarf Medaka). Thailand, Cambodia, southern China, Phuket Island, Chao Phraya and Mekong river basins. 17 mm. Transparent fish with blue eyes, often perceived as the fry of other fish. In males, the anal fin is convex, the front rays of the dorsal and anal fins are elongated. In females, the anal fin is slightly concave. T 23-30°C; pH 6.0-7.5;
Due to their small size, they should be kept in a large school in a species aquarium. Dwarf shrimp can be added to them. It is better to use dark substrate, patches of dense vegetation, and several open swimming areas. Place twisted roots and driftwood on the bottom, and let some floating plants with long roots drift on the surface. Medium-hard water with a pH above 7 is favorable for maintenance.
For feeding, use small live and frozen food, cyclops, daphnia, artemia, and dried products of appropriate size. They pick up food from the bottom reluctantly. Females carry a cluster of fertilized eggs numbering from 2 to 9, and then the eggs, upon contact, stick singly or in small clusters to plants. After hatching, the fry rush to the water surface, where they can hide among the roots of floating plants.
Identification: Genus Oryzias — Oryzias.
Oryzias javanicus, latipes, woworae.
Nomorhamphus celebensis, Nomorhamphus liemi. 
