Harlequin Rasbora
(Trigonostigma heteromorpha )
Temperature: 70 - 82 F
pH: 5.5 - 7.0
dGH / dKH: 1 - 10
Community Fish - Yes
Size: 1.5-2.0 in.
Difficulty: Easy
The Harlequin Rasbora originates from parts of South East Asia, specifically found in soft inland water systems. Despite being native to these types of waters, these fish are excellent at adapting to almost any freshwater tank. This, paired with its superb ability to get along with others is why rasboras in general are a great choice for the first time fish keeper. In the home aquarium, the harlequin rasbora will appreciate water that is more on the soft acidic side. A temperature from 70 to 82 F, pH in the range of 5.5 to 7.0 and a dGH and dKH between 1 and 10. This fish will reproduce, especially in the planted aquarium, but only if the parameters consist of warm, soft acidic water.
A small peaceful swimmer, the harliquin rasbora is extremely similar in coloring and is often mixed up with two other species of Trigonostigma. Harliquins have a more oval shaped body and more of a grey coloration in contrast to a deeper red found on the other two species. The predominant black triangle that resembles a t bone steak on the rasbora is its most notable feature, spanning from the dorsal to caudle fin. This feature will also be more triangle shaped on the harlequin when compared to the very similar lamchop rasbora.
Harlequin Rasbora Care Sheet
These guys are great schooling fish and will want to be part of a medium to large sized shoal, I recommend starting out with at least 6 of them. They will behave best this way and you’ll get the most activity out of them. No need to worry much about tank size when keeping this fish, as they only get to be about to 1.5 to 2 inches when fully grown. As long as your tank is 10 gallons or more, you should be just fine with a small school. Females are identified as being fuller and not as brightly colored as their male counterparts, although this isn’t a perfect way to tell the two apart.
A true omnivore feeding on small insects and macro algae in the wild, the harlequin rasbora loves pretty much anything you throw at it. From your standard flake and freeze dried blood worms to live foods, these guys will chow it down. Just make sure you crush up the food small enough for them to get a hold of. Overall, the Harliquin rasobora is a fan favorite. Perfect for the beginner fish keeper or someone who’s looking to keep a dynamic schooling fish in their planted tank.
