The success of any aquaculture endeavour broadly depends on water quality. Water quality determines to a great extent the success or failure of aquaculture operation. Optimum water quality is considered necessary for any aquaculture operation as it influences the productivity of production system. In the present review, the role of major abiotic factors such as water pH and hardness on the biological processes of fish like growth, survival, reproductive performance and embryology has been discussed.
The mince of rohu (Labeo rohita) fish was used to develop susages using microbial transglutaminase (MTGase). The functional (gel strength, water holding capacity, folding score), textural, colour characterstics, protein pattern and microstructure of the mince sausages prepared using MTGase (0, 1, 1.5 & 2%) were studied. MTGase positively enhaced the gel strength, water holding capacity, and folding score of the prepared sausages with an increment in concentration of MTGase. MTGase effectively cross-linked proteins in the gel network as revealed in protein patterns, despite presence of sarcoplasmic proteins. Although low, but the gel strength of mince sausages was found to be comparable with surimi and surimi-based gel products. The different concentration of MTGase did not show any significant influence (p > 0.05) on the textural properties of susages such as hardness, cohesiveness, adhesiveness and elasticity. The variation in colour characteristics of cooked mince sausages particularly whiteness arises from the pigments in mince and the colour of MTGase used during formulation of sausages. MTGase added sausage samples had a finer and homogenous protein network with a smaller void when compared with the gel of mince without MTGase in microstructure analysis. Though potential additive for improvement of functional properties of sausages, availability and cost of MTGase limits its use in the development of value-added fish products such as sausages from mince of freshwater fish.
The aim of this study was to evaluate the effect of letrozole (a non-steroidal aromatase inhibitor) on masculinization of Siamese fighting fish (Betta splendens). Different doses of letrozole 50, 100, 150 and 200 ppm (mg/kg feed) were incorporated into diet and fed for periods of 30, 40 or 50 days. Immersion treatment of letrozole at selected doses (250, 500, 750 and 1,000μg/l) for 3 h each on third, fifth and eighth day-post-hatching (dph) (Trial 1) and fourth, sixth and eighth dph (Trial 2) was given.The oral administration of letrozole for 30, 40 or 50 days did not have any significant effect on the sex ratio of B. splendens. The immersion treatment of letrozole induced 100% masculinization at 500 and 1000μg/l in trial 1, while it yielded only 66.66 and 90% male population at 500 and 1000 μg/l in Trial 2. The dietary administration of letrozole for 30 and 50 days caused tail deformities and/or rudimentary and absence of dorsal fin. The progeny testing of males from letrozole treated (both oral and immersion) groups indicate that the sex ratio of progenies of each of the males tested did not differ significantly from that of control, indicating that all those males carried XY genotype. Letrozole treatments suppressed ovarian development (atretic oocytes were common). However, the testicular development was unaffected. The study revealed that immersion treatment of letrozole was more effective in inducing masculinization of B. splendens than the oral administration of letrozole.
The present study was conducted to study the effect of 17α-methyltestosterone (17α-MT) on masculinizationefficiency through immersion treatment in dwarf gourami, Trichogaster lalius. The immersion treatment of 17α-MT at doses of 250, 500, 750 and 1000 μg/l was carried out for 3 h daily on third, fifth and eighth day after hatching. The highest concentrations of 17α-MT produced the highest percentage of males (84.29%). The progeny testing of males from17α-MT treated groups indicated that the female progenies of each of the males tested differ significantly from that of control, indicating that all those males carried XX genotype. The gonado-somatic indexof the hormone treated fish revealed significant suppression of the ovarian development.
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