Betadevario ramachandrani

Betadevario: named for beta, the second letter in Greek alphabet, also representing the numeral 2, and used in the meaning of second, and also the name of Beta Mahatvaraj 'who made great efforts to make the material available for this study'; and –devario. With reference to its similarity to the genus Devario, in the meaning of second Devario.

ramachandrani: named for Professor Alappat Ramachandran, School of Industrial Fisheries, Cochin University of Science and Technology, Kochi 'in recognition of his contributions fisheries and sea food production management and studies on indigenous ornamental fishes'.

Known only from two sites in the upper Sita River drainage close to the village of Agumbe, Karnataka state, southwestern India.

Type locality is given as 'India: Karnataka: Dakshina Kannada: Shimoga District: Agumbe, small stream tributary to Sita River, 2 km upstream from Onake Abbi Fall (13°30’79’’N 75°4’49’’E), 558 m ASL'.

The Sita flows through part of the Western Ghats mountain range and by current knowledge B. ramachandrani is the only danionin endemic to that region, though some others do occur there.

Agumbe is among the rainiest places in India, on average receiving just short of 8000 mm per year, and lies in a heavily-forested area of the Western Ghats mountain range close to the Someshwara Wildlife Sanctuary and Kudremukh National Park.

The region is well-known as a biodiversity hotspot and is home to numerous locally endemic fish species.

The type locality is a shallow (maximum depth ~30 cm12 in), high-altitude stream located at 558 metres AMSL.

It consisted of a series of cascades and small pools and was just 2-3 metres wide at time of collection. The only other fish reported there was an unidentified Schistura sp.

A tank with a base measuring 120 ∗ 30 cm48 ∗ 12 in or equivalent should be the minimum considered for this active species.

Not difficult to keep in a well-maintained set-up though we recommend aquascaping the tank to resemble a flowing stream or river with a substrate of variably-sized, water-worn rocks, sand, fine gravel and perhaps some small boulders.

This can be further furnished with driftwood roots or branches, and while the majority of aquatic plants will fail to thrive in such surroundings hardy types such as Microsorum, Bolbitis or Anubias spp. can be grown attached to the décor.

Since it naturally occurs in pristine habitats it's intolerant to accumulation of organic pollutants and requires more-or-less spotless water in order to thrive.

Though very fast flow is unnecessary it also does best if there is a high proportion of dissolved oxygen and moderate water movement, while weekly water changes of 30-50% tank volume should be considered routine.

The tank must also have a very tightly-fitting cover as it's likely to be an accomplished jumper.

Temperature: Water temperature at the type locality was measured as 66°F/18.9°C in December 2007 but in aquaria a range of 18 – 23 °C64 – 73 °F should prove acceptable.

pH: 6.0 – 7.0

Hardness: 2 – 10 dGH

Like the majority of relatives this species is almost certain to prey chiefly on insects and their larvae in nature although 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.

Not an aggressive fish but likely to stress less active tankmates with its constant movement and vigorous feeding behaviour making it appropriate only for communities containing robust, similarly-sized fishes.

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

A community comprising species from the Western Ghats could also make a worthwhile project with species available in the trade including Dawksinia arulius, Haludaria fasciata, Puntius sahyadriensis, Barilius canarensis, Rasbora daniconius, Botia striata, Garra bicornuta plus various Schistura spp.

It's a schooling species by nature and really should be kept in a group of at least 8-10 specimens.

Maintaining it in decent numbers will not only make the fish less nervous but result in a more effective, natural-looking display, plus males will display their best colours as they compete with one other for female attention.

Sexually mature females are should be rounder-bellied and a little larger than males but otherwise appear very similar.

It's unknown if males intensify in colour when spawning as in many related species.

We know of no reports as yet but like other danionins this species should be an egg-scattering spawner showing no parental care.

As far as we know this species is yet to arrive to the international aquarium trade though it has been maintained by a handful of Indian aquarists.

Its restricted geographical range and difficulty of collection mean it's unlikely to become available in numbers unless adopted by commercial breeders.

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) Devario spp. are characterised by: possession of a P stripe extending onto the median caudal fin rays; a short maxillary barbel (absent in some species); absence of the A stripe (a less distinct, relatively wide stripe is present in some species, e.g., D. acrostomus, D. annandalei, D. xyrops); a short, wide premaxillary process (cleft in the upper jaw) with a tiny apophysis (bony tubercule) touching the kinethmoid bone; infraorbital 5 not or slightly reduced.

Brachydanio spp. possess an A stripe on the anal-fin and two or more P stripes on the caudal-fin, plus some internal characteristics such as enlarged nasal lamellae and a median projection on the pleural rib of the fourth vertebra.

Betadevario is intriguing as it exhibits physical characteristics normally associated with either Brachydanio or Devario spp. but not both.

Externally it most resembles members of the former since it possesses much longer barbels than any species of Devario and a prominent A stripe.

However it lacks enlarged nasal lamellae, the median rib projection and has only a single P stripe on the caudal-fin while possessing the internal characters usually diagnostic for Devario.

Morphologically it therefore appears to fall somewhere between Brachydanio and the striped group of Devario spp.

The species was also subject to molecular analysis with results placing it as sister group to Devario and Microrasbora, occupying a basal position within this clade of three genera.

It may thus represent a relict species confined to a small portion of the Western Ghats; a theory supported by the overall high level of endemism in the region (in excess of 40% of fish species occurring there are currently reported as endemic).

Molecular analyses by Fang et al. (2009) and Tang et al. (2010) have confirmed that within the family Cyprinidae this 'Devario clade' is most closely-related to a 'Danio clade' containing the genera Brachydanio, Danio and Danionella plus an 'Esomus clade' which groups Esomus alongside Paedocypris and Sundadanio.