Exclamation Point Rasbora

The exclamation point rasbora is one of the smallest members of the genus Boraras; adults reach about 1.5 cm. Its golden-orange or brownish body has a dark stripe running from the middle to the tail, with a distinct dot on the caudal peduncle at the end of the stripe. Together, the stripe and the dot resemble an exclamation point lying on its side. Males show a bright reddish-gold line above the stripe and red-orange fins.

It adapts to a somewhat wider range of water values than the Borneo species of the genus, which makes it a species that beginners can also keep successfully in nano aquariums. Even so, it needs a mature, calm aquarium.

It lives in the lowlands of Indochina, in shallow, heavily vegetated swamps, ponds, ditches and rice paddies. The water is still or very slow-flowing and usually soft and slightly acidic. Dense aquatic plants provide both shelter and a food source.

• Volume: at least 20 liters for a group of 10–15.
• Water: 23–27°C, pH 6–7, soft to moderately hard water.
• Plants: very dense planting, moss and floating plants; leave a small open area at the front.
• Flow: weak; a sponge filter is ideal.
• Tankmates: only species as small and calm as itself.

It is a micropredator with a very small mouth. It accepts micro granules and flakes ground to powder; supplement with newly hatched brine shrimp, cyclops and microworms. Giving small portions two or three times a day is better than giving a lot of food at once.

Peaceful and calm. It moves among the plants in loose groups; males display to each other by flaring their fins and may hold small territories. The squabbles are harmless.

Good companions: Neocaridina and Caridina shrimp, other Boraras species, celestial pearl danios, otocinclus, small snails.

Avoid: any fish with a mouth big enough to swallow it; medium-sized and active species, including bettas; fast schooling fish that outcompete it for food.

At least 10, ideally 15 or more individuals. In a large group the males show more color and the fish come out into the open. The male-to-female ratio is not critical; having slightly more females spreads out the males' displays.

It deposits its eggs among moss and fine-leaved plants, and sometimes on the underside of leaves. In a mature aquarium with moss, fry may appear on their own. For controlled breeding, soft water, plenty of moss and a small container are enough; the adults are removed after spawning. The fry are fed infusoria for the first days, then newly hatched brine shrimp.

• Starvation: the most common problem is not offering food that is small enough.
• Water quality: in a small volume, values change quickly; do 20–30% water changes weekly.
• Acclimation: acclimate new fish slowly and in dim light.

Males are slimmer; the reddish-gold line above the stripe and the red-orange fins are prominent. Females are plumper, with paler, yellowish colors.