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Based on the annual length frequency data collected from three major fish landing centres along the River Periyar, draining the southern Western Ghats, the von Bertalanffy growth function (VBGF) estimates of Horobagrus brachysoma were worked out as asymptotic length (L a ) = 422mm total length, growth co-efficient (K) = 0.55 yr -1 and growth performance index (ø) = 4.99. The total mortality rate (Z) was estimated at 5.64 yr -1 , natural mortality rate (M) at 1.04 yr -1 , fishing mortality (F) at 4.60 yr -1 , and exploitation rate (E) at 0.82 yr -1 . Yield per recruit (expected lifetime yield per fish recruited in the stock at a specific age) analysis showed an excessive fishing effort. Using the analysis of probability of capture of each length class, the length at first capture (L c ) of H. brachysoma was estimated to be 110mm. An indication of both growth and recruitment fishing is provided by the dominance of year 1 class in the exploited population and the capture of immature individuals below first maturity. Management of H. brachysoma fishing should include setting of a minimum mesh size limit of 160-180 mm for gill nets as well as a closed season starting from the month of May till August aimed at protecting the spawning stock. This study on H. brachysoma, an endemic and threatened catfish of peninsular India, provides hard evidence that species targeted by artisanal fishermen, in small-scale tropical riverine fisheries, are vulnerable to overexploitation.

Indiscriminate and illegal farming of the African Catfish Clarias gariepinus, in central Kerala has now resulted in the escape and spread of the species into Vembanad Lake, a large brackish water wetland and inland fish diversity hotspot. We collected 17 individuals of C. gariepinus ranging in size from 200 to 750 mm from different locations in the southern sector of the lake during a field survey conducted in 2007. Samples comprised of mature specimens of both sexes indicating their reproductive potential in the study area. The possible impacts of spread of C. gariepinus into natural water bodies of Kerala, especially the Vembanad Lake, and options for their management are discussed.

Lepidopygopsis, known as the peninsular-Indian hill trout, is a monotypic genus endemic to the Periyar stream-reservoir system, in the Western Ghats. Due to the morphological similarity of its only species, L. typus, with the Himalayan schizothoracine fishes, it was considered to be a relict species and a classic example of disjunct distribution. Using mitochondrial and nuclear gene sequence datasets, we show that L. typus is not allied to the schizothoracine fishes. Phylogenetic hypothesis-testing unequivocally supports a scenario in which L. typus and a clade comprising various genera of Asian and African barbins such as Tor, Gonoproktopterus, Kosswigobarbus and Varicorhinus are sister groups. Based on our results, we suggest that the sheath of tile-like scales covering the anal-fin base of schizothoracine fishes and Lepidopygopsis typus could be a symplesiomorphy or a homoplasy.

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The Western Ghats of India harbours an exceptional diversity of endemic freshwater fishes, which are threatened because of various anthropogenic stressors, including biological resource use. Lack of organized studies on the population dynamics and exploitation levels of endemic species, however, has hindered the development and implementation of systematic conservation action plans in this region. This is especially true for large cyprinid fishes threatened because of overharvest. This study examined length–weight relationships and length‐structured population dynamics of an endemic large cyprinid (Hypselobarbus kurali), based on data obtained from an artisanal gill‐net fishery in Malampuzha Reservoir. Length–weight analysis suggested the fish exhibited significantly lower exponents than expected under isometry, indicating the growth of H. kurali in the reservoir was negative allometric. The von Bertalanffy growth formula fitted to the length‐frequency data indicated H. kurali grew relatively slower than other large cyprinids in this region. Statistical analysis of recruitment revealed two peaks, implying the fish have two spawning bouts each year. Analysis of mortality and exploitation of the species revealed large‐sized individuals were targeted by the fishers, resulting in an exponential decline in the survivors in the virtual population analysis. Relative yield‐per‐recruit and relative biomass‐per‐recruit analysis indicated the current exploitation rate for the population was greater than the exploitation rate under which the stock would be reduced to half its unexploited biomass. Further, the current exploitation level was more than 60% of the expected maximum exploitation above which the population could collapse. The results of this study identify a serious need to develop and implement management plans to guide the future sustainability of the reservoir fishery of H. kurali.