The genus name is a corruption of the original name Rasbora. Yes, boraras were separated from rasboras in 1993 when describing the species Boraras micros. The genus includes 5 species. Of these so-called microrasboras (they are also found in the genus Microrasbora), Boraras maculatus (formerly Rasbora maculata, the dwarf rasbora) was formerly the main species. Nowadays, new species are appearing, but so far we can only admire them in photographs from import companies. For example, Microrasbora sp. “Galaxy” is becoming a hit, a tiny species discovered somewhere in Myanmar only a few months ago, which is making its way all over the world (and can be bought even at Papik’s).
Boraras are often very nicely colored and are also trouble-free keepers, but due to their size (max. 3 cm) they are not suitable for a classic community aquarium. Therefore, they are very rarely seen in shops. I first saw the sign Boraras brigittae two and a half years ago and immediately bought six of them (by the way, two of them are still alive today). As it turned out later, the correct name is Boraras urophthalmoides – B. brigittae is a very similar species, but I have not seen it here yet. Biotope is also the only retailer that often has boraras on offer. Still under the misnomer B. brigittae, however.
Boraras urophthalmoides
was until relatively recently a fish in our area, the existence of which was known only to “connoisseurs”. However, as you will have noticed in our Gallery of mini aquaria, it is nowadays one of the hits. Its size, low requirements and relatively good availability make it perhaps the most desirable fish species for mini aquariums.
Its homeland is Thailand and Vietnam, where it is found in smaller water tanks or ditches. It does not need a large space, on the contrary, it avoids open areas – small schools move in dense vegetation and look for food, which consists of small animals.
The maximum size of this species is 1.6-2 cm. It is a peaceful, schooling fish that is suitable for community aquariums – provided, of course, that its tankmates are of a reasonable size. For this reason, it is mainly found in small specialist aquariums or in nature aquariums, where, together with a few other species and shrimps, it forms a complement to plants. You won’t enjoy a school of these fish kept alone, they will become shy – so it is advisable to combine them with other dwarfs.
I have 6 fishes in my aquarium in the company of a school of Corydoras pygmaeus and this coexistence seems to suit everyone. The pygmies, with their relentless activity, calm the fishes that were initially hiding in the plants, so now they come to the windscreen to see them. Moreover, the pygmies occasionally get confused and, seeing the longitudinal stripe, hang on the rasbora’s fins and wonder why they don’t play with them 🙂
Boraras urophthalmoides requires a densely vegetated tank, soft and slightly acidic water. Another requirement is a reasonable size of food – snails or threadfins are out of the question, but even regular sized flakes are an excessive morsel for them. So there is no choice but to give them larger pieces of food. My razorbills love (as do all my fish from dwarfs to cichlids) Nutrafin crumbled tablets. Almost daily, though, they get live nauplii artemia, which is their main food. For variety I give them frozen cyclops occasionally (they almost ignore it). They prefer to take their food from the water column, but they have learned to search the bottom with their armadillos. They stay close to the bottom most of the time, they rarely come to the surface.
The only difference between the male and female is the shape of the body: the female has a rounder belly, the male looks a little more rickety. Different sources also indicate a difference in colouration (a light spot in the dorsal fin, or a generally more varied colouration of the males – neither of which I have found in my fish). They supposedly spawn in the morning, usually several days in a row. Java moss works best as a substrate for them; it is advisable to add peat to the bottom of the tank. Boraras are found in nature in black waters with low pH – this is a good thing to keep in mind if we want to be as successful as possible in rearing.
The parents will eat the eggs, but if they spawn in a tank that is densely overgrown, we can also get a brood here without catching the adults. Similar cases are published on the internet from time to time, but overall the breeding of this species is one of the great success stories. Very small live food is a prerequisite. The spawn hatches in 40-50 hours and emerges in 4 to 5 days.
Boraras urophthalmoides is a sympathetic fish. It is one of the few species really suitable for small aquariums. It doesn’t have a very interesting behaviour, like most schooling fish – the charm lies in the school, which moves a bit erratically and jerkily through the aquarium. As the angle of the light hitting them changes, the fish cast reflections in different colours. Their big eyes watch me closely whenever I approach the aquarium. And I can’t resist throwing them something to eat…
Boraras maculatus
is a more familiar, if now much less common, relative. It grows a little larger (commonly 2.5 cm), but otherwise has much the same characteristics and requirements. In good conditions, the fish turn a beautiful red colour and are fearless, making them a real addition to a small aquarium.
Breeding can also take place in the tank with the parents if we have enough aquatic plants, especially Java moss (Vesicularia dubyana). Again, a low pH is a prerequisite – in the home of this species it often drops below 5!