Danio meghalayensis

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

meghalayensis: named for the Indian state of Meghalaya, to which it is considered endemic.

So far only known from the East Khasi Hills district of Meghalaya State, north-east India.

The type series was collected near Umiam Lake, also known as Barapani.

The whole area is around 1200 m AMSL and the southern slopes of the Khasi Hills receive the highest annual rainfall in the world.

Even a small group needs an aquarium with base measurements of 120 ∗ 45 cm48 ∗ 18 in or more.

Looks particularly effective in a heavily-planted arrangement with a darker substrate, and may appear paler in sparsely-decorated set-ups.

We suggest maintaining it in a well-planted aquarium or 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.

Additional powerhead(s) or filter outlets can be used to provide flow but torrent-like conditions should be avoided as small Danio spp. such as this tend to occupy calmer stretches and marginal zones in nature.

Driftwood roots, branches and aquatic plants, with hardy genera such as Microsorum, Bolbitis or Anubias ideal since they can be grown attached to the décor, can also be added.

The aquarium must have a very tightly-fitting cover as members of this genus are accomplished jumpers and can fit through surprisingly small gaps.

Temperature: Air temperatures in Meghalaya vary from sub-zero in winter to around 82.4°F/28°C in summer so it's best kept in an unheated tank and tends to struggle if maintained above 77°F/25°C for prolonged periods. A range of 16 – 21 °C61 – 70 °F should prove adequate for aquarium care provided both aeration and feeding are increased during warmer months.

pH: 6.5 – 7.5

Hardness: 2 – 15 dGH

Probably preys on insects and their larvae in nature. In the aquarium it's largely an unfussy feeder and will accept most foods.

A good quality dried product or two 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 fish to show the best colouration and conditioning.

Not an aggressive fish but may upset very slow-moving or timid tankmates with its constant activity and vigorous feeding behaviour so can only be considered appropriate for larger tanks containing robust, similarly-sized fishes.

There are plenty of suitable choices including many cyprinids, loaches, cichlids, catfish and characins although as always when selecting a compatible community of fish proper research is essential.

A community based around species from Meghalaya could also include Devario aequipinnatus, Barilius bendelisis, Acanthocobitis botia, Botia dario and Lepidocephalichthys guntea.

It's a schooling species by nature and should be kept in a group of at least 8-10. Maintaining it in decent numbers will not only make the fish less nervous but result in a more effective, natural looking display.

Any aggressiveness will normally also be contained as individuals concentrate on maintaining their hierarchical position within the group, and males will display their best colours in the presence of conspecific rivals.

Mature males are more colourful, noticeably slimmer, and smaller than females, and they possess a greater proportion of red pigmentation in the fins.

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

If the fish are in good condition they should spawn often, and in a densely-planted, mature aquarium it's possible that small numbers of fry may start to appear without intervention.

In general, however, D. meghalayensis has proven tricker than other danios with the usual methods tending not to yield results.

When only a single pair is used the larger females tends to chase the male incessantly, for example, and the only successful report we know of is that of U.S. aquarist Dennis Ball whose group of 8 adult fish spawned during a thunder storm following a period of being conditioned with live foods.

Although a clump of Taxiphylum was present in the aquarium the fish chose to spawn within the coarse gravel substrate with the females leading and males behind.

Once spawning had ended the adults were removed.

The first fry were observed approximately 48 hours after the spawning event and became free-swimming after a further 48 hours.

From this point onwards they were offered Artemia nauplii and branded fry foods, and grew very quickly reaching 12 – 15 mm0.5 – 0.6 in within 30 days.

Thanks to Dennis Ball.

This species was considered a form of D. dangila for a number of years until 2004 when full species status was reinstated by Fang.

It's since been available in the trade on a sporadic basis and is much sought after by Danio enthusiasts.

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.

Following Fang (2003) Danio spp. are characterised by the presence of an A stripe on the anal-fin and two or more P stripes on the caudal, plus some internal characteristics such as enlarged nasal lamellae.

The genus 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.

The currently obsolete name 'Brachydanio' was often adopted for members of the latter group and is seen in much of the older aquarium literature.

However in 2003 Fang 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 generic 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) have resulted in further changes.

Unfortunately while these works agree in some aspects they frequently contradict each other, notably in the usage of the subfamily names Rasborinae (Weber and de Baeufort, 1916) and Danioninae (Bleeker, 1863), the positioning of D. kyathit in relation to D. rerio and the degree of relatedness between Danio and Esomus species.

The species formerly known as Microrasbora erythromicron was found to be grouped within Danio in both sets of results.

At present SF follows the results of Fang et al. (2009), thus Danio is considered to be composed of three sub-clades, i.e., groupings of closely-related species.

The first comprises D. erythromicron, D. margaritatus, D. choprae and D. flagrans.

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, whereas all other Danio spp. have lateral or horizontal stripes on the body and relatively long barbels.

There's a suggestion that D. erythromicron and D. margaritatus will be moved again in the future as the two share morphological and behavioural aspects that appear to set them apart from other danios.

The second clade contains the type species, D. dangila, 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 D. dangila group is also likely to contain D. meghayalensis and D. feegradei.

The remaining species, of which D. rerio is thought to be the most ancient, are included in the third sub-clade, and there is a possibility these three groups may eventually be separated into different genera.