Hill Stream Fish Research Articles

Dimorphic Morphological Features between Sexes of Semiplotus semiplotus McClelland

Understanding of secondary sexual dimorphism in fish is an uphill task and the phenomenon is paradoxical in different species. Considering the importance, a study was carried out to identify the distinguishing morphological characters between the sexes of Semiplotus semiplotus(McClelland). It is a hill-stream fish species endemic to Eastern Himalayas and also important as food. Statistical analysis of various morphological measurements and meristic counts of 30 numbers of freshly collected specimens was the tool of the study. Together, some morphological peculiarities have also been noted for the seasonal sexual dimorphism. The females were found having longer anal fin height than the males by an average of 3.96 mm. Again, the formation of keratinized tubercles on the anal fin of males versus smooth anal fin in females was also observed during breeding season. However, meristic counts were similar in both the sexes. Key words: Sexual dimorphism, anal fin, tuberclesDOI: 10.3126/on.v7i1.2564Our Nature (2009) 7:158-162

Seasonal Distribution and Relative Abundance of Fish Fauna of a Small Hill-Stream Dangchaura (Takoli) Gad, along with River Alaknanda

The present study was carried out to investigate seasonal distribution and relative abundance of fish fauna of a small hill stream Dangchaura (Takoli) Gad along with river Alaknanda. The differences in availability of fish-fauna were directly related to the nature of profile and slope of tributary; which affects the migration and breeding grounds of the fishes inhabited in the main river Alaknanda.Key words: Hill-stream fish fauna, Seasonal distribution, Dangchaura GadDOI: 10.3126/on.v7i1.2569Our Nature (2009) 7:182-186

Adhesive apparatus in certain Indian hill stream fishes

The results of a detailed study on the adhesive apparatus of Indian hill stream cyprinid and sisorid fishes are presented. The structure of the mental suctorial disc in the genus Garra is described. Histological study of the mental region of Crossocheilus and Psilorhynchus has also been made and compared with the mental disc of Garra. The muscles of the disc which control its movements in bringing a partial vacuum during adhesion have been investigated. The complexity of the geniohyoideus muscles in Garra is interesting. Variations in the degree of development and histological modifications of the mental disc are exhibited by the fishes of the genus Garra.A thoracic adhesive apparatus in the form of longitudinal or transverse ridges and grooves is present in the sisorids, Laguvia, Glyptothorax and Pseudecheneis except Gagata. A close study has revealed that the adhesive apparatus of the catfishes works mainly on the principle of friction. The variations in shape, size and location of the adhesive apparatus in various species are correlated to their respective habitats.Structural variation in the adhesive apparatus of Pseudecheneis is maximum in comparison to that in Laguvia and Glyptothorax. It is discovered that the modifications are associated with the presence of multi‐spinous layers, formation of caps by the basal or holdfast cells and with the transformation of loose areolar tissue into thick collagenous dermis. The presence of a pad of adipose tissue in the region of the adhesive apparatus has been reported and its physiological significance as a source of stored food suggested.The anterior part of the protractor ischii muscle is modified to control the action of the adhesive apparatus. In Pseudecheneis, besides the m. protractor ischii, the ventral part of m. mesioventral is also associated with the adhesive apparatus.

The pelvic girdle and fin in certain Indian hill stream fishes

This paper deals with the functional morphology of the pelvic girdle and fins in various genera of hill stream cyprinid and sisorid fishes. The pelvic plate of Pseudecheneis shows the greatest modification; it is unusually large and reaches the coracoids of the pectoral arch in front.The elaborate working of the pelvic muscles and their function in bringing about effective adhesion by the pelvic fins is described in detail. The formation of a new muscle, M. pars retractor ischii of the M. mesioventralis, is reported in Garra and Psilorhynchus (Cyprinidae) and in Glyptothorax and Pseudecheneis (Sisoridae). In Pseudecheneis, the complete separation of this muscle from the M. mesioventral, and modification of the M. protractor ischii, are discussed in relation to the crawling habit of the genus. The appearance of the M. arrector pel vicalis ventralis in Glyptothorax and Pseudecheneis among sisorids has been associated with the adhesive function of the outer ray.

The Adhesive Apparatus of the "Sucking-fish"

EARLY in 1923 I published in NATURE a short summary of my views regarding the mechanism of the so-called suckers of certain hill-stream fishes and of the “Sucking-fish” —Echeneis.1 My conclusions were based on an examination of the living specimens of two Indian genera of hill-stream fishes—Pseudecheneis and Glyptothorax, and on a study of preserved material of Echeneis. Later, at my request, Major R. B. Seymour Sewell, Surgeon-Naturalist to the Marine Survey of India, very kindly performed a series of experiments on living specimens of Echeneis. Quite recently (September 1924) I have been able to conduct a few experiments on the “Sucking-fish” in the Marine Aquarium at Madras. In carrying out these experiments I received great help from Dr. Sundara Raj, acting director of the Madras Fisheries, and Prof. H. Parameswaran, of the Presidency College.