Boraras Species Guide: 5 Micro Rasboras Compared

Introduction to Boraras
The 5 Boraras Species Compared
Boraras brigittae (Chili Rasbora)
Boraras maculatus (Dwarf Rasbora)
Boraras merah (Phoenix Rasbora)
Boraras micros (Micro Rasbora)
Boraras urophthalmoides (Least Rasbora)
Tank Setup for Singapore
Feeding Micro Foods
Planted Tank Pairing
Frequently Asked Questions

Introduction to Boraras

The genus Boraras contains the smallest cyprinids in the hobby, and every single one of them is a gem. These micro rasboras — all under two centimetres — have become the darlings of nano aquascaping, and for good reason. In a beautifully planted tank, a school of Boraras creates movement and colour at a scale that larger fish simply cannot match.

For Singapore hobbyists, Boraras carry an additional advantage: they originate from Southeast Asia. Our warm tap water temperatures and naturally soft-to-moderate water chemistry suit them well. At Gensou, with over 20 years of aquascaping experience in Singapore, we have kept and bred all five species. This guide shares what we have learnt.

The 5 Boraras Species Compared

Species	Common Name	Max Size	Colour	Temperament	SG Availability	SG Temp Suitability
B. brigittae	Chili Rasbora	1.5 – 2 cm	Deep red with dark lateral stripe	Shy, peaceful	Common	Excellent
B. maculatus	Dwarf Rasbora	1.5 – 2 cm	Orange-red with dark spots	Slightly bolder	Common	Excellent
B. merah	Phoenix Rasbora	1.5 – 2 cm	Red-orange with dark blotch	Shy, peaceful	Moderate	Excellent
B. micros	Micro Rasbora	1 – 1.3 cm	Pale yellow-green with spots	Very shy	Uncommon	Excellent
B. urophthalmoides	Least Rasbora / Exclamation Point	1.5 – 1.8 cm	Gold with dark stripe and tail spot	Bolder than others	Moderate	Excellent

Boraras brigittae (Chili Rasbora)

The undisputed star of the genus. B. brigittae displays a deep, saturated red that intensifies dramatically in mature, well-conditioned specimens. A dark lateral stripe runs from snout to caudal peduncle, bordered above and below by the signature crimson. Males develop deeper colour than females, particularly when displaying.

Chili rasboras are the most popular Boraras in Singapore and readily available at most local fish shops. They are slightly shy at first but become confident in large groups within a planted tank. For a detailed deep-dive, see our chili rasbora care guide.

Boraras maculatus (Dwarf Rasbora)

Often the first Boraras newcomers encounter, B. maculatus is slightly bolder than its cousins and a touch easier to keep. Its colouration is orange-red rather than deep crimson, with three distinct dark spots — one at the base of the caudal fin, one below the dorsal fin, and one behind the gill plate.

This species is native to Peninsular Malaysia, southern Thailand and parts of Sumatra, making it practically a local fish. It handles Singapore’s water conditions with zero complaints and is widely available at affordable prices.

Boraras merah (Phoenix Rasbora)

The phoenix rasbora is sometimes confused with B. brigittae, and the two are indeed closely related. B. merah tends to display a more orange tone compared to the deeper red of chilis, with a prominent dark blotch on the flank rather than a continuous stripe. The distinction becomes clearer when you see both species side by side.

In Singapore, B. merah is less commonly stocked than chilis or dwarf rasboras, but specialist shops carry them periodically. They share identical care requirements with other Boraras species.

Boraras micros (Micro Rasbora)

At barely one centimetre, B. micros is the smallest of the genus and one of the smallest freshwater fish kept in the hobby. Its colouration is subtler — a pale yellowish-green body with a pattern of dark spots. It lacks the dramatic reds of its cousins, which makes it less popular commercially.

However, in a well-lit nano tank with a dark substrate and dense plantings, a large school of B. micros has an understated elegance. They are the most challenging Boraras to find in Singapore, so expect to pay a premium when they appear.

Boraras urophthalmoides (Least Rasbora)

The “exclamation point rasbora” earns its nickname from the distinctive marking pattern: a dark horizontal dash on the body followed by a prominent round spot at the tail base, resembling a punctuation mark. Body colour ranges from gold to orange-red depending on conditions and diet.

B. urophthalmoides is notably bolder than other Boraras species. It spends more time in open water and is less prone to hiding in vegetation. This makes it an excellent choice if you want Boraras behaviour without the frustration of fish that disappear into the plants the moment you approach the tank.

Tank Setup for Singapore

Tank Size

Boraras are true nano fish. A school of 10 to 15 can thrive in a 20-litre tank, though 30 to 45 litres provides more stable water parameters and a better display. In Singapore’s HDB flats and condos where space is at a premium, these fish let you create a stunning aquascape on a desk or shelf.

Water Parameters

Parameter	Ideal Range	Notes for Singapore
Temperature	24 – 30 °C	Ambient SG temperatures are perfect
pH	5.0 – 7.0	Prefer acidic; use botanicals or aqua soil
GH	1 – 8 dGH	Soft water preferred
KH	1 – 5 dKH	Low buffering fine with active substrate

Singapore’s PUB tap water, once treated for chloramine, is moderately soft and works well for Boraras. For best colour development, use an active aqua soil substrate (such as ADA Amazonia) which naturally lowers pH. Adding Indian almond leaves or alder cones provides tannins that mimic their blackwater origins.

Filtration

Use a gentle sponge filter or a small hang-on-back filter with a pre-filter sponge. Boraras are tiny and weak swimmers — strong currents stress them. In nano tanks, an air-driven sponge filter is ideal: it provides biological filtration and gentle surface agitation without creating flow that overwhelms these miniature fish.

Schooling Numbers

Keep Boraras in groups of 10 or more. This is not merely a suggestion — it is essential. In small groups, they hide constantly and never develop confident behaviour or full colour. A school of 15 to 20 in a well-planted nano is transformative: the fish form loose shoals, males display to one another, and their colours intensify dramatically.

Feeding Micro Foods

Boraras have tiny mouths, and standard flake or pellet food is too large. You need micro-sized foods.

Staple: Crushed high-quality flake (ground to powder) or dedicated micro pellets
Live foods: Vinegar eels, microworms, baby brine shrimp (BBS), infusoria
Frozen: Cyclops, daphnia (small strain), crushed frozen bloodworm
Prepared: Hikari First Bites, Sera Micron — both readily available in Singapore

Feed small amounts twice daily. In a mature planted tank with biofilm on surfaces, Boraras will also graze naturally between feedings. This supplemental grazing contributes to their health and is another reason why planted tanks suit them so well.

Planted Tank Pairing

Boraras look their absolute best in densely planted aquascapes. The green backdrop makes their red and orange hues pop, and the plants provide security that encourages confident behaviour.

Recommended Plant Combinations

Background: Rotala rotundifolia, Ludwigia species, Hygrophila pinnatifida
Midground: Cryptocoryne species (excellent in SG conditions), Bucephalandra
Foreground: Eleocharis (dwarf hairgrass), Monte Carlo, Marsilea hirsuta
Floating: Salvinia, Limnobium (provides shade and security)

The combination of floating plants filtering light and dense stem plants providing cover creates the dim, sheltered environment Boraras prefer. Visit us at Gensou, 5 Everton Park to see Boraras in our planted display tanks.

Compatible Tank Mates

Due to their size, Boraras must be kept with equally gentle species:

Neocaridina shrimp (cherry, blue velvet)
Otocinclus
Small Corydoras (pygmy, habrosus)
Other Boraras species (though do not mix if breeding)
Snails (nerite, ramshorn)

Avoid any fish large enough to eat them, and steer clear of aggressive species. Even a single betta can terrorise a Boraras school in a small tank.

Frequently Asked Questions

Can I mix different Boraras species in one tank?

Yes, different Boraras species coexist peacefully. However, they may interbreed, producing hybrid offspring. If you want to breed a specific species, keep them separately. For a display-only tank, mixing species creates a beautiful multi-toned red and orange effect. Ensure each species is kept in groups of at least 8 to 10 so they school with their own kind.

Why are my Boraras pale and hiding?

This usually indicates one of three issues: the group is too small (add more fish), the tank lacks plant cover (add floating plants and dense vegetation), or water parameters are off (test pH, ammonia, nitrite). New Boraras often take two to four weeks to settle in and develop full colour. Patience and stable conditions are key. In Singapore’s warm climate, also ensure your nano tank is not overheating beyond 32 degrees — use a small fan if needed.

How long do Boraras live?

With proper care, Boraras species live three to five years. This is respectable for such tiny fish. Stable water parameters, varied micro foods and a stress-free environment are the keys to longevity. Our aquarium maintenance services can help keep nano tank conditions optimal.

Do Boraras need a heater in Singapore?

No. Singapore’s ambient temperatures of 28 to 32 degrees Celsius fall within their comfort range. If your tank is in an air-conditioned room that drops below 24 degrees consistently, a small adjustable heater is a good safeguard. For most setups, heaters are unnecessary.

Start Your Boraras Nano Tank

Boraras micro rasboras prove that incredible things come in tiny packages. Whether you choose the fiery chili, the bold exclamation point or the subtle micro, these fish transform planted nano tanks into living jewels.

Visit us at Gensou, 5 Everton Park, Singapore to see Boraras in our planted displays and discuss your nano aquascape project. With over two decades of experience in Singapore aquascaping, we will help you select the perfect species and design a tank that brings out their best.

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