Redtail Rice Fish

Species Profile

• Scientific Name: Oryzias mekongensis
• Common Name: Redtail Rice Fish
• Adult Size: 2.5 to 3 cm (1 to 1.2 inches)
• Life Expectancy: 2 to 4 years in optimal conditions
• Habitat: Shallow, slow-moving waters such as rice paddies, ditches, and lowland streams in the Mekong River Basin (primarily Thailand, Laos, and Cambodia). These environments often feature dense aquatic vegetation and soft, slightly acidic water.

Tank Requirements

• Minimum Tank Size: 5 gallons (10+ gallons recommended for a group)
• Ideal Temperature: 22–28°C (72–82°F)
• pH Range: 6.0–7.5
• Water Hardness: 2–12 dGH (soft to moderately hard)
• Temperament: Peaceful and calm. Best kept in small groups of 6 or more. Suitable for nano tanks and peaceful community setups with similarly sized fish.

Diet & Nutrition

• Omnivorous: Yes. Will eat a variety of foods, including:

  • High-quality micro-pellets and flakes
  • Live and frozen foods such as brine shrimp, daphnia, and microworms
  • Occasional plant-based foods or spirulina to ensure balanced nutrition

Appearance

• Body Color: Pale to translucent body with a silvery sheen
• Tail & Fins: Distinctive bright red to orange caudal (tail) fin, which gives the species its common name
• Size: Small and slender, with a soft iridescent glow under proper lighting

Distinctive Features

• Bright red tail is the standout feature, contrasting with the otherwise clear to silver body
• Hardy and adaptable, making them a good choice for beginner nano tank keepers
• Naturally occurring in rice paddies—symbolic of Southeast Asian aquatic biodiversity
• Display best coloration in well-planted tanks with subdued lighting and dark substrates