Accepted 29th, August, 2014
Study of fish gills are complex and are suited for gaseous and ionic exchange in extreme conditions of their habitat. The present paper deals with the histological study of gill filaments and gill rakers from post flexion to fingerling stages of snow trout schizothorax plagiostomus. For collecting the post flexon to finger stage larvae induced breeding were conducted on the bank of Alaknanda during the month of October-November, 2006 by stripping method. The number of gill filaments and gill rakers increases as the size of the S. plagiostomus larvae increases.The gill filaments are arranged in two rows on a gill arch, while the gill rakers are arranged in one or two rows on the gill arch. Morphologically the rakers are soft and long in each gill arch. The gill filaments are also soft and long. They are directly related to their feeding nature and food quality. In the present study of post-flexion to fingerling stage of Schizothorax plagiostomus larvae the gill apparatus, i.e. Gill arch, filaments, and rakers were easily distinguishable around the buccopharyngeal region. Some blood channels were also recognizable in this stage and pseudobranch arch or area was more developed or elongated and having close resemblance to the gill filaments. Blood channels with R.B.Cs. like substances as in gills were noticed in pseudobranch. Formation of secondary lamellae with marginal channels was apparent in the section of 1.0-2.0cm. larvae of S. plagiostomus. Also in this stage, the branchial arteries were discernible in each gill arch. Gill cover was elongated. A group of pillar cells were recognizable and within these groups of cells the blood channels were apparent among the 8.0 cm. larvae. Thus, the blood channels of secondary lamellae were lined by pillar cells (mesenchymal cells).
Keywords: Schizothorax plagiostomus, Histological, Post flexion stage, Fingerling Stage