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P. K. Pati , B. C. Guru and P. Routray
 The habitat ecology of freshwater crab Sartoriana spinigera was studied for a period of two years (January 2010-December 2011) in two distinct ecosystems viz., the canal and the ponds in three districts of eastern Odisha (Cuttack, Kendrapara and Bhadrak). These crabs were available in good numbers in the monsoon season in these districts with two peaks of abundance in each year. During the first and second year of study the total crab availability showed a greater peak in the month of August and lower in the month of April. It was found that the freshwater crab S.spinigera required an optimal habitat having a sandy clay soil. The water parameters in the study sites were found varied such as temperature 24.36 to35.19C, pH 5.9 to 7.6, conductivity 0.423 to 0.461µS/cm, dissolved oxygen 3.4 to 6.9mg/l, free CO° 13.3 to 18.2 mg/l, total alkalinity 115 to 156 mg/l, phosphate 0.012to 0.036 mg/l, ammonia nitrogen 0.008 to 0.053 mg/l and nitrate nitrogen 0.041 to0.054 mg/l. Similarly, the sample crabs required different soil parameters in their habitats: pH 6.5-7.3, organic carbon 0.45-0.63 mg/l, nitrogen 8.28-8.84 mg/phosphate 1.23-1.86 mg/l and conductivity 0.053-0.072 µS/cm. Further, it was observed that to support the scavenging and omnivorous food habits of such crabs,a rich growth of micro flora and fauna was essential in their habitat. The gut content analysis of such crabs showed the presence of phytoplankton, zooplanktons like copepods, ostracods, amphipods, isopods along with crustacean larvae and their appendages, molluscan larvae, eggs of fishes, certain unidentified species and soil. This study confirmed the food habit of crabs and thus explained the role of these crabs in the food web of their habitats. 2

Keyword: The habitat ecology of freshwater crab Sartoriana spinigera was studied for a period of two years
S. Das , K. D. Mahapatra, J. N. Saha, J. Odegard and P. K. Sahoo 1
 Full-sib families of rohu (Labeo rohita) of four year-classes viz., 2003 (906 numbers offish), 2004 (1208 nos.), 2008 (2000 nos.) and 2009 (1355 nos.) were subjected tointraperitoneal Aeromonas hydrophila challenge. The fingerlings were tagged individually with passive integrated transponder (PIT) tag and total length was measured prior to challenge. The mortality was recorded on an hourly basis for upto 24 h and later over a period of 10 days post-challenge. Mean body length of survived and dead fish were significantly different (p<0.05) in the year-classes2004, 2008 and 2009, whereas for 2003 there was no marked difference. Positive correlations of 0.004, 0.115 and 0.108 were found between length and survival for2004, 2008 and 2009 year-classes, respectively. However, the length of 2003 yearclassshowed a negligible negative correlation (-0.065) with survival. The serum immune parameters viz., haemolysin titre, ceruloplasmin and myeloperoxidase activities analyzed from naïve individuals of each family showed positive correlations with body length of the same family (0.135, 0.290 and 0.109, respectively) in three year-classes i.e., 2003, 2004 and 2009. The positive correlation of length with survival and immune response indicated its possibility to be used asa co-trait for selection for improved resistance to A. hydrophila infection.

Keyword: Full-sib families of rohu (Labeo rohita) of four year-classes
Deepak Ranjan Sahoo, Samiran Nandi and Jyotirmaya Mohanty
 Vitellogenin (Vtg) is the yolk precursor protein in fish and is synthesized in the liver under estradiol-17ß (E2) stimulation. In all oviparous animals, Vtg issynthesized as a response to endogenous estrogen in females in the breeding season. It also could be induced exogenously by E2 in males and juveniles. In thecurrent study the inducibility of Vtg gene in Indian major carp, Catla catla wastested. A semi-quantitative reverse transcriptase-polymerase chain reaction (RTPCR)assay was developed for kinetic study of Vtg mRNA level in C. catla after primary and secondary inductions by E2. It was found that the level of Vtg-specificmRNA was highest following 12 h post treatment in primary induction, and after 1 d post treatment in secondary induction. There was a sharp decrease in VtgmRNA level on day one and day two in primary and secondary induction, respectively. Thus the ‘memory effect’ of vitellogenin induction by E2 in catla could not be confirmed.  

Keyword: Vitellogenin (Vtg) is the yolk precursor protein in fish and is synthesized in the liver under estradiol
S. P. Das, D. Bej, S. Swain, J. K. Jena and P. Das
Keyword: The age of Indian major carp, Cirrhinus mrigala
 The age of Indian major carp, Cirrhinus mrigala (Hamilton, 1822) was determined from 208 specimens from five peninsular rivers (Mahanadi, Godavari, Kaveri,Narmada and Mahi) of India by observing the annual rings in scale. Using length frequency method and scale study, it was found that only River Mahiholds6+yearclassof C. mrigala stocks. A strong linear relationship was found between fish length and scale radius of this species in all the riverine populations, with significant correlation coefficient. The first growth ring was found at an average length of 27.86, 28.86, 37.22, 26.77 and 25.59 cm in specimens from Mahanadi,Godavari, Kaveri, Narmada and Mahi, respectively.  It is evident from our result that the fishes exhibited rapid growth rate during the first two years of their age but later, growth was moderate. Growth rate decreased successively at higher ages. 

Nibedita Rana, and Basanta K Das
The genus Dactylogyrus is the largest helminth genus with more than 900 species (Neary et al., 2012). It represents the most dominant genus among the monogenean with regards to host distribution and location. These are common ectoparasites living in gills of freshwater fishes (Woo, 2006). They seem to be an appropriate model for studying the process of parasite diversification, mainly because of their high species richness and,morphological and ecological diversity. They are attached to the host surface by acharacteristic opisthaptor which is species-specific and has anchors, hooks and hook lets (order: Monopisthocotylea). These are hermaphroditic flatworms of aquatic vertebrates.

Keyword: The genus Dactylogyrus is the largest helminth genus with more than 900 species