Danio flagrans

Danio: from Dhani, a Bengalese vernacular term for small, minnow-like cyprinids.

flagrans: a Latin participial adjective meaning flaming, blazing, burning, glowing, and is used in allusion to the red to orange colour, with inspiration from the common name 'glowlight danio'.

Known only from a handful of streams in the upper Mali Hka river drainage, Ayeyarwaddy River system, near Putao township in the far north of Kachin state, northern Myanmar.

Type locality is 'Nan Hto Chaung in Putao, about 1 mile from 46th regiment, close to rice mill'.

Apparently displays a preference for small hill streams with substrates of gravel and variably-sized rocks.

Images we've seen of habitats in Putao depict a narrow stream with rocky margins and dense surrounding vegetation. Some stretches appear to be shallow and fast-flowing with others deeper and more sluggish.

When the type series was collected in March 1998 the Nan Hto Chaung stream was almost dried up, only around 50 cm20 in in width and contained no other fishes.

It empties into a larger stream, the Nan Hto, but no danios were collected there.

A second locality, Londont Chaung, was around 2 m wide and 1 m deep with fast-moving, cold water, no aquatic vegetation, and a substrate of sand, gravel, boulders and driftwood. The water temperature was 16.7 °C62 °F, pH 8.2 and conductivity 93 μS · cm−1.

A third site also contained cool, flowing water and lacked aquatic vegetation but was up to 4 m wide and 2 m deep with fast-moving sections broken up by pools with slower flow. Parameters here were temperature 17 °C63 °F, pH 7.77 and conductivity 55 μS · cm−1.

Base dimensions of 80 ∗ 30 cm31 ∗ 12 in or larger are required for this active species.

Looks particularly effective in a heavily-planted arrangement with a darkish substrate, and can appear a little washed out in sparsely-decorated set-ups.

We suggest keeping it in a well-planted aquarium or alternatively it would look superb in a set-up designed to resemble a flowing river or stream with a substrate of variably-sized rocks and gravel and some large water-worn boulders.

The water should be well-oxygenated with a degree of flow although torrent-like conditions should be avoided since small danionins tend to occupy calmer stretches and marginal zones in nature.

The tank can be further furnished with driftwood branches and hardy aquatic plants such as Microsorum, Bolbitis or Anubias spp. which can be grown attached to the décor.

The aquarium must have a very tightly-fitting cover as this species is an accomplished jumper and can fit through surprisingly small gaps.

Almost certain to prey chiefly on insects and their larvae in nature. In the aquarium it's a largely unfussy feeder and will accept most foods.

A good quality dried product can be used as the staple diet but this should be supplemented with regular meals of small live and frozen fare such as bloodworm, Daphnia, Artemia, etc., for the best colouration and conditioning.

Generally very peaceful making it an ideal resident of the well-furnished community tank.

Since it places no special demands in terms of water chemistry it can be combined with many of the most popular fish in the hobby including other small cyprinids as well as tetras, livebearers, rainbowfish, anabantoids, catfish and loaches.

A community based around stream-dwelling species from the Irrawaddy/Ayeyarwady basin would also make an interesting project with possibilities including Badis kyar, Acanthocobitis botia, Botia histrionica, B. rostrata, Lepidocephalichthys berdmorei, Schistura vinciguerrae, Crossocheilus latius, Danio albolineatus, Pethia didi, P. erythromycter, P. stoliczkanus, P. ticto, Devario apogon, 'Inlecypris' shanensis, and Rasbora daniconius among others.

It's a schooling species by nature and really should be kept in a group of at least 8-10 specimens which will develop a pecking order among themselves.

Maintaining it in decent numbers will therefore not only help make the fish less nervous but will allow sub-dominant fish of both sexes some respite from the alpha male(s) which can be quite aggressive at times.

It's not uncommon to see nipped fins in lesser individuals within a group though this behaviour does not normally extend to tankmates.

Sexually mature females are usually rounder-bellied, less colourful and a little larger than males.

Nuptial males are likely to intensify in colour.

Unconfirmed but should be similar to related species. Here follow recommendations for D. choprae:

Like many small cyprinids this species is an egg-scattering spawner that exhibits no parental care.

That is to say when the fish are in good condition they will spawn often and in a densely-planted, mature aquarium it is possible that small numbers of fry may start to appear without human intervention.

However if you want to increase the yield of fry a slightly more controlled approach is required.

The adult group can still be conditioned together but one or more smaller, say 10-15 litre, containers should also be set up and half-filled with water.

These should be very dimly lit and the base covered with some kind of mesh of a large enough grade so that the eggs can fall through it but small enough so that the adults cannot reach them.

The widely available plastic 'grass'-type matting can also be used and works very well; alternatively filling much of the tank with Java moss or other fine-leaved plant can also yield good results.

The water itself should be of slightly acidic to neutral pH with a temperature towards the upper end of the range suggested above.

A small power filter can be added initially and this should be positioned so that the flow is directed down the full length of the tank.

When the adult fish are well-conditioned and the females appear full of eggs one or two pairs should then be introduced to each container.

Spawning can be initiated by adding small amounts of cool water every few hours in such a way that the tank is gradually topped up and feeding small amounts of live and frozen foods.

The pair should spawn the following morning. The easiest and quickest way to tell is simply to look at the female. If the fish have spawned she will be noticeably slimmer.

he adults will eat any eggs they find and are best removed after a couple of days at which point the power filter should be switched for a mature sponge-type unit in order to avoid fry being sucked into the mechanism.

Incubation is temperature-dependant to an extent but usually takes around 72 hours with the young free-swimming a couple of days later.

Initial food should be Paramecium or or a proprietary dry food of sufficiently small (5-50 micron diameter) grade, introducing Artemia nauplii, microworm, etc., once the fry are large enough to accept them.

This species has been available in the aquarium hobby in limited numbers and also traded as 'Danio sp. Putao', 'D. putaoensis' or 'D. cf. choprae'.

It looks very similar to D. choprae and these two are distinguished from other danios by their shared colour pattern consisting of several vertical bars on the flanks, followed by postabdominal P and P+1 stripes, a distinct P+2 stripe anterior to the dorsal-fin, and red stripes between the middorsa'l and P+2 stripes, and between the P and P+1 stripes. Both also possess well-developed tubercles on the infraorbital ossicles.

It can be told apart from D. choprae by the following characters: body more slender (22.5-26.6 % SL vs. 26.6-31.6% SL in D. choprae); caudal peduncle longer (20.5-24.7 % SL vs. 16.1-19.1 % SL); base of anal-fin shorter (14.2-18.3 % SL vs. 19.2- 23.9 % SL); rostral barbels longer (10.3-18.7 % SL vs. 5.9-10.1 % SL), reaching beyond the preopercular margin in adults (vs. not reaching posterior margin of orbit); maxillary barbels longer, reaching to below base of pectoral-fin base (vs. not reaching base of pectoral-fin); lateral line almost always present, with up to seven perforated scales (vs. almost always absent, occasionally up to three perforated scales); more vertebrae contained in caudal peduncle (9-10 vs. 6-8); 9½-11½ branched anal-fin rays (vs. 12½-13½, rarely 11½); base of anal-fin hyaline (vs. base of anal-fin dark); no black streak in lower lobe of caudal-fin (vs. usually present).

In recent years it's become commonplace to refer to the stripes on the body and fins of danionins as follows:

- P stripe: or "pigment stripe" is the central, dark, lateral stripe on the body which extends into the caudal-fin in some species. Stripes above it are numbered P+1, P+2, etc. and those beneath P-1, P-2, P-3.
- A stripe: the central stripe on the anal-fin; the proximal stripe (above it) is A+1 and the distal stripe (beneath) A-1.
- D stripe: The submarginal dorsal-fin stripe.

The putative danionin grouping has undergone some significant taxonomic reshuffling in recent years following the publication of a series of phylogenetic studies.

Older, molecular, phylogenies tended to agree that it represented a monophyletic group consisting of two major clades; the 'Danio devario' group containing the larger, deeper-bodied species and the 'D. rerio' clade comprising the smaller, slimmer fish.

However in 2003 Fang conducted a more detailed study based on morphological characters which included members of other related genera, and the results suggested for the first time that the genus Danio as previously considered represents a polyphyletic grouping, i.e., not all members derived from a single common ancestor.

The genus name Devario was suggested for the larger species with Danio being applied only to the smaller fish (with the exception of the type species, D. dangila which can grow to around 89 mm3.5 in SL). Recent molecular studies by Mayden et al. (2007) and Fang et al. (2009) resulted in further changes, with the latter study considering the genus Danio to be composed of three subclades. These were subsequently split into distinct genera by Kottelat (2013), as follows:

The former species D. erythromicron, D. margaritatus, D. choprae and D. flagrans were grouped together in the revalidated genus Celestichthys Roberts, 2007. These exhibit unique body patterning consisting of vertical bars (D. erythromicron, D. choprae, D. flagrans) or light spots (D. margaritatus) and possess either very short barbels or none at all.

Kottelat (2013) left only the type species, D. dangila, in Danio, separated on the basis of its larger size and the shape of the caudal-fin, which in adults is only slightly emarginate or even truncate in shape, a feature it shares only with Tinca tinca (the common tench) among other cyprinids.

The remaining species, of which D. rerio is thought to be the most ancient, were placed in the revalidated genus Brachydanio Weber & de Beaufort, 1916. Kullander (2015) did not follow this split, because phylogenetic analyses strongly support a single Danio in the sense of Fang (2003), with Devario a separate genus. The Catalog of Fishes and FishBase both keep all of these species in Danio.