Koyna River is one of the five Indian rivers which find their source at the Pachaganga Temple in Mahabaleshwar within the Sahyadri mountain range (also known as the Western Ghats); they’re also home to one of India’s few evergreen forests. This range forms a barrier to the Deccan Plateau for the monsoon winds and as the clouds are forced to rise when they meet the mountains, this leads to large amounts of rain fall, particularly during the rainy season (June till September) and give rise to the formation of rainforests. The area is known as one of the most biodiverse places on earth with a high degree of endemism. Geologically seen, it was formed after the Godwana breakup.
Koyna river is one of the major tributaries to the Krishna river, the fourth biggest river in India. Koyna River flows in a southward direction for about 65km, turns sharply eastwards at Helwak, in which direction it flows until its confluence with the Krishna River at Karad; stream velocity, temperature and pH in this river system are highly influenced by monsoon.
This aquarium I present here is based on a small stream that drains into Koyna river, close to its confluence with Krishna River; it is well oxygenated and the water is relatively soft with temperature varying between 17-27°C and pH at around 6,8-7,5.
No macrophytes can be found in this system and the river bed is dominated by gravel and cobbles of different sizes among sandy substrate.The Zebra Loach Botia striata and the Giant Danio Devario aequipinnatus live in sympatry with several other fish species in these waters such as the Bombay Labeo Labeo porcellus, Jerdon’s Carp Hypselobarbus jerdoni, Rohtee ogilbii, the endangered Schismatorhynchos nukta, the Black Mahseer Tor khudree (also endangered) and Neotropius khavalcho which was listed as a threatened species in the 2004 Karnataka Environmental Report; the Cyprinidae are the dominant group with the beautiful and endemic Maharaja Barb Puntius sahyadriensis in greatest numbers, althiough it is a species which seems to have disappeared in the aquarium hobby.
Western Ghats freshwater fish are threatened by a broad range of human activities: deforestation leading to siltation and a dramatic change in the riverbed structure, damming, agricultural run-off, untreated wastewater discharges and many others; some areas of Koyna river system are relatively less threatened by anthropogenic pressures, although this is the minority.
One positive note is that a major part of the Koyna River backwaters are protected by the Koyna Wildlife Sanctuary, forming a safe haven for the endemic fishes, essential in conservation.
Botia striata is a habitat specialist within a relatively small area and the pressure on other river systems it lives in cannot be ignored. Raghavan et al published a shocking report in 2013 entitled “Uncovering an obscure trade: Threatened freshwater fishes and the aquarium pet markets” within which the stand-out comment which highlights the extreme uncertainty of the future of Botia striata was
“Of the 1.5 million individual threatened freshwater fish exported, the major share was contributed by three species; Botia striata (Endangered), Carinotetraodon travancoricus (Vulnerable) and the Red Lined Torpedo Barbs (a species complex primarily consisting of Puntius denisonii and Puntius chalakkudiensis, both ‘Endangered’)”.
Chris Englezou, founder of the Freshwater Life Project, a charitiable organisation helping to bridge the gap between the aquarium industry and the conservation sector stated “It is a complex issue which must be met with sustainability rather than prohibition in order to safeguard the future of the fishes, the people and the entire ecosystems”.
I’d like to think that the biotope aquarium hobby could be a catalyst for contributing to the protection of species like the Zebra Loach with ex-situ breeding programs helping to satisfy some of the localised international demand – although that is no easy task! On the larger scale, something must be done to incentivise the protection of the habitat (and thus, the fishes).