Max Size: 10cm

Simons Rasbora (Rasbora simonbirchi)

Simon Rasboras are a very peaceful and adaptable species making them an ideal member of a larger, well-furnished community aquarium. In addition, these Rasboras have no special demands when it comes to water chemistry; therefore, you can combine them with multiple of the most popular fish in the hobby.

Ideal tank mates for the Rasbora simonbirchi could include other Cyprinids as well as Livebearers, Tetras, Gouramis, Rainbowfish, Catfish and Loaches. Creating a community aquarium based around one of their River Basins or native countries would also be a worthwhile project with some exciting alternatives.

The Simon Rasbora is sociable by nature; therefore, it would be best to keep them in a group of at least six individuals, although keeping more will get the best out of them in the aquarium. Then, like most fish, they will display better colours in the presence of their kind, will be less anxious, and the display, on the whole, will be more natural-looking.

Choosing decor is not as crucial as water quality and open swimming space. Keeping these fish in a large, well-planted aquarium or a set-up designed to resemble a flowing river would be much better for them.

The substrate should consist of gravel, different sized rocks or smooth boulders, and you could also construct a river tank manifold to provide natural unidirectional flow. You can further furnish the tank with aquatic plants and driftwood branches for aesthetic value.

While most plant species will fail to thrive in these conditions, hardy species such as Java fern, Bolbitis or Anubias grown attached to the decor is possible.

The aquarium needs to have a very tightly-fitting lid as these Rasboras are surface-dwelling species that are accomplished jumpers and can escape through the tiniest of gaps.

Simon Rasboras are intolerant to the build-up of organic waste; therefore, it is crucial that you perform regular water changes for your fish to thrive as the water in their natural habitats is pristine.

Simon Rasboras have a silvery to salmon pink body colouration and possesses a mid-lateral black stripe that shines an iridescent green that starts from the posterior margin of the eye through to the caudal fin. These Rasboras also display an overlying series of crescent-shaped black marks along the posterior margins of the midlateral scales and a faint small black blotch situated above the anal fin. All of their fins are transparent with a slightly reddish-orange hue.

Quick Facts
Scientific NameRasbora simonbirchi
Other NamesNone
Aquarium LevelMiddle - Top
Best kept asGroups 6+
Lifespan4 - 8 years
Water Parameters
Water TypeFreshwater
PH6.0 - 7.5
GH2 - 12
73 - 79℉
22.8 - 26.1℃

Photos of the Simons Rasbora

Simons Rasbora
Simons Rasbora

Natural Habitat

Simon Rasboras are endemic to the middle Barito River Basin of Central Kalimantan in Borneo in Southeast Asia. These Rasboras generally inhabit blackwater rivers and streams associated with old forest peat swamps. The water is usually stained a brown colour due to the discharge of tannins and other chemicals released by decomposing organic material. The substrate is generally covered with fallen leaves, branches and twigs. These habitats typically contain soft, acidic water and are often dimly lit due to the forest shelter above.

What to feed the Simons Rasbora

Simon Rasboras are not fussy and are relatively easy to feed. However, they will do much better on a varied diet. Therefore, it would be best to provide them with appropriate sized, good-quality dried foods such as flakes and granules alongside regular offerings of live, frozen and freeze-dried food such as bloodworms, tubifex, brine shrimp and daphnia.

How to sex the Simons Rasbora

It is somewhat challenging to differentiate between the male and female Simon Rasbora; however, Sexually mature females are rounder in their bellies, are often a little larger than males, and usually have lighter colouration.

How to breed the Simons Rasbora

Currently, there is no information available on how to breed Simon Rasboras; however, one can imagine that they would produce like most small Cyprinids. Therefore these fish will likely be egg scattering, constant spawners that present no parental care.

In a heavily planted, established aquarium, small numbers of fry may start to appear without intervention. However, if you would like to increase the yield of fry, a more controlled approach will be required.

You can condition the adult group together; however, you need to set up a separate breeding tank. It would help if you dimly lighted this tank and covered the bottom with some mesh with large enough holes for eggs to fall through but small enough holes so the adults cannot reach them or leave it bare. You can also use plastic grass matting, pebbles or marbles; these work pretty well.

The water itself should have a slightly acidic to neutral pH, and the temperature needs to be marginally higher than the general aquarium. You can add an internal power filter initially, and you should position this so that the flow is directed down the entire tank length.

Once the adult fish are well-conditioned and the females are noticeably full of eggs, you should introduce one or two pairs to the breeding tank. You can encourage spawning by either adding small amounts of cooler water every few hours so that the tank is gradually topped and feeding them live and frozen foods several times throughout the day.

The adults will probably consume any eggs they find if given a chance, so it would be better if you removed them after a couple of days. At that point, you should take out the power filter and swap it for a sponge filter to avoid babies being sucked into it.

The incubation period is temperature-dependent; however, it usually takes between 18 and 48 hours for the eggs to hatch. The young will become free-swimming around 24 to 48 hours later.

You should initially provide your fry with Paramecium or infusoria, introducing baby brine shrimp and microworm once the fry is large enough to accept them.

Other Rasboras of interest

Black Line Rasbora(Rasbora borapetensis)
Chilli Rasbora(Boraras Brigittae)
Clown Rasbora(Rasbora kalochroma)
Dwarf Rasbora(Boraras maculatus)
Emerald Eye Rasbora(Brevibora dorsiocellata)
Exclamation Point Rasbora(Boraras urophthalmoides)
View all Rasboras
Date Added: 25/01/2022 13:00:25 - Updated: 25/01/2022 13:19:15