Exclamation Point Rasbora
Exclamation Point Rasbora (Boraras urophthalmoides) earns its common name from the distinctive body pattern of males: a bold black lateral dash followed by a bright red or orange spot near the tail base — a pattern that, viewed from the side, reads unmistakably like an exclamation point. At just 0.6 inches, it is among the smallest fish regularly kept in the aquarium hobby.
Feeding & Care Tip: The Exclamation Point Rasbora's mouth is extremely small. Start juveniles on Sera Micron Nature and transition to Sera Vipan Baby flakes as they mature. Supplement 2–3× per week with Hikari Frozen or Freeze-Dried Baby Brine Shrimp. Feed small amounts 2–3 times daily.
Native to slow-moving forest streams and peat swamps across Thailand, Vietnam, and the Malaysian peninsula, this species inhabits tea-colored blackwater with very soft, acidic conditions. In the aquarium, soft slightly acidic water, dark substrate, gentle flow, and tannin additions replicate its natural environment and produce the richest color.
Keep in groups of at least eight, preferably twelve or more. Larger groups produce more confident behavior and noticeably brighter coloration — males in a large group display constantly, keeping colors at peak intensity. Best kept with other tiny, peaceful species such as other Boraras, small shrimp, or similarly sized nano fish.
In a well-planted nano aquarium, a school of Exclamation Point Rasboras creates an electric, constantly moving splash of color. Their small size makes them compatible with even the most delicate planted layouts.
Care & Ideal Parameters
| Difficulty | Easy |
| Temperament | Peaceful — Nano Community |
| Typical Adult Size | 0.6 inches (1.5 cm) |
| Min. Group Size | 8 minimum — groups of 12+ produce significantly brighter color |
| Ideal Temp | 68–82°F (20–28°C) |
| Ideal pH | 6.0–7.0 |
| Ideal GH | 1–6 dGH |
| Ideal KH | 0–4 dKH |
| Staple Food | Sera Micron Nature (juveniles); Sera Vipan Baby (adults) |
| Treat / Supplement | Hikari Frozen or Freeze-Dried Baby Brine Shrimp |
| Origin | Thailand, Vietnam, Malaysia |
| Notes | One of the smallest aquarium fish. Sera Micron Nature for juveniles, Sera Vipan Baby for adults. Best in nano or species-specific setups only. |
