Sahyadria chalakkudiensis

Sahyadria: named after Sahyadri, noun, a vernacular name for the Western Ghats mountain ranges.

chalakkudiensis: named for the Chalakudy/Chalakkudy River in Kerala, India, type locality of this species.

Initially considered endemic to the Chalakudy River system in Kerala state, southern India, but subsequently recorded from the Periyar, Pamba, and Achankovil rivers.

Type locality is given as 'Chalakkudi River, Western Ghats, Trichur, Kerala, India'.

A stream and river-dwelling species most often found in middle parts of river basins where it typically congregates in rocky pools with dense riparian vegetation and substrates of sand, gravel, or bedrock.

Base dimensions of at least 120 ∗ 45 cm48 ∗ 18 in or equivalent are required.

Not difficult to keep in a well-maintained aquarium, though perhaps best suited to a set-up designed to resemble a flowing stream or river with a substrate of variably-sized, water-worn rocks, sand, fine gravel and driftwood.

Since it naturally occurs in pristine habitats it is intolerant to accumulation of organic pollutants and requires more-or-less spotless water in order to thrive. It also does best if there is a high proportion of dissolved oxygen and moderate water movement, and weekly water changes of 30 -50% tank volume should be considered routine.

Wild fish on a variety of worms, insects, crustaceans, plant material, and other organic debris.

In the aquarium it is easily-fed but a balanced diet comprising regular meals of small live and frozen foods such as chironomid larvae (bloodworm), Daphnia, and Artemia alongside good quality dried products will being about optimal condition and colours. Sinking foods are best.

It is said that the red pigmentation can be intensified by feeding a diet rich in carotenoids such as astaxanthin.

Can be belligerent and is unsuitable for the general community aquarium. Robust, similarly-sized cyprinids, characids, catfishes, and perhaps larger botiid loaches constitute the best choices in terms of tankmates.

Though gregarious by nature it is a shoaling rather than schooling species which develops a distinct pecking order, and therefore should always be maintained in a group of five or more. If only two or three are present the subdominant fish may be subjected to excessive antagonism.

Adult females tend to grow a little larger, are heavier-bodied, and a little less colourful than males.

Unrecorded but presumably a seasonal spawner in nature like its congener S. denisonii.

This species was first exported for the aquarium hobby in 1996, with the fish collected from the bottom of a waterfall in the Chalakudy River basin, Kerala and identified as S. denisonii based on colour pattern, although the latter may not have been traded until 2001.

Additional confusion arose when the name Puntius chalakkudiensis was mistakenly assigned to a fish of the genus Dawkinsia by Indian exporters prior to publication of its official description, and as a result other members of that genus, such as D. assimilis, have been sold under the name at times.

This species was formerly considered to be a member of the genus Puntius, a polyphyletic catch-all which contained over 100 species, although this situation has been largely resolved since the turn of the century.

Sahyadria was raised by Raghavan et al. (2013) in order to accommodate S. chalakkudiensis and its only congener S. denisonii. The genus is diagnosed by the following combination of characters: adult size 85 – 190 mm3.3 – 7 in SL; a single pair of maxillary barbels; dorsal fin with 3-4 unbranched and eight branched rays, posterior branched ray sometimes bifurcate at the base giving the appearance of a 9th branched ray, posterior unbranched ray weak, segmented apically, unserrated; anal fin with 2-3 unbranched and five branched rays; lateral line complete, with 26–28 pored scales; free uroneural absent; gill rakers simple, acuminate, arranged in two rows with 12 and 18 rakers respectively; antrorse predorsal ray absent; post-epiphysial fontanelle absent: 5 supraneurals; infraorbital IO3 slender, not overlapping preoperculum; 5+3+2 pharyngeal teeth; 16 abdominal and 11 caudal vertebrae; colour pattern comprising an upper scarlet stripe extending from snout to midbody, a wide blackish lateral stripe extending along the lateral line from snout to caudal-fin base, a yellow stripe extending from the operculum to the hypural region between the black and scarlet stripes, caudal fin lobes with oblique black bands covering the posterior quarter and subterminal oblique yellow bands, dorsal fin with or without a black blotch: juveniles with scarlet pigmentation on the anterior dorsal-fin rays.

S. chalakkudiensis can be told apart from S. denisonii by possession of an inferior mouth (vs. subterminal), presence of a black marking in the dorsal-fin (vs. absence), and the scarlet body stripe being duller and terminating beneath or anterior to the dorsal-fin origin (vs. brighter and terminating beneath the centre of the dorsal-fin).