Black Harlequin Rasbora
Black Harlequin Rasbora (Trigonostigma heteromorpha) is a selectively bred melanistic variant of the classic Harlequin Rasbora. The entire body takes on a deep charcoal to black coloration — a bold, graphic fish that makes a striking contrast alongside the standard copper or purple harlequin forms.
Feeding & Care Tip: Hikari Micro Pellets make an excellent daily staple. Supplement 2–3× per week with Hikari Frozen or Freeze-Dried Tubifex Worms or Hikari Frozen or Freeze-Dried Baby Brine Shrimp. High-quality varied feeding helps maintain the deep black pigmentation. Feed small amounts 2–3 times daily.
Care requirements are identical to the standard Harlequin Rasbora. The black body coloration is most dramatic against lighter green plants — the contrast of jet black fish against bright green aquatic plants is very striking.
Keep in groups of at least six, preferably ten or more. Particularly effective when kept in a mixed school alongside the standard Harlequin or Purple Harlequin forms — three color expressions of the same species.
An excellent choice for aquarists wanting to add a dark, dramatic element to a schooling community tank.
Care & Ideal Parameters
| Difficulty | Easy |
| Temperament | Peaceful — Community |
| Typical Adult Size | 1.75 inches (4.5 cm) |
| Min. Group Size | 6 minimum — groups of 12+ produce more natural schooling behavior |
| Ideal Temp | 72–82°F (22–28°C) |
| Ideal pH | 6.0–7.0 |
| Ideal GH | 2–8 dGH |
| Ideal KH | 1–6 dKH |
| Staple Food | Hikari Micro Pellets |
| Treat / Supplement | Hikari Frozen or Freeze-Dried Tubifex Worms, Hikari Frozen or Freeze-Dried Baby Brine Shrimp |
| Origin | Captive-bred cultivar of Malaysian/Thai wild stock |
| Notes | Melanistic cultivar of standard Harlequin Rasbora — care identical. Bold black coloration most dramatic against bright green plants. |
