پژوهش های ماهی شناسی کاربردی
سال:1392 | دوره:1 | شماره:3 |تعداد مقالات:8

Trichlorophon is one of the organophosphate poisons that are used with different objectives in aquaculture. The current study dealt with the measurement of acute toxicity caused by Trichlorophon on six species of ornamental fish, namely the red sword tail, Tiger, Barbie, bright tetra, guppies, Green-fin molly and Gambusia. To this end, all species were exposed to 5 treatments (with three replicates for each treatment) under different concentrations of toxin containing 0, 5, 10, 20 and 40 ppm They were treated for 96 hours and the rate of mortality was recorded. Toxicity tests were determined using probit analysis in the statistical software SPSS (version 16). At the end of the experiment, the LC50 96 hours of Trichlorophon in the red sword tail, Tiger, Barbie, bright tetra, guppies, Green-fin molly and Gambusia were 7.99, 8.74, 8.88, 9.80, 9.80 and 9.95 mg/liter, respectively. Eventually, Trichlorophon was classified as partly toxic for ornamental fish causingvery similar lethal ranges for all six species, though the red sword tail fish was more sensitive to this toxin.

The present paper aimed at evaluating the nutritional value and fatty acid profile of muscle in cultivated cyprinids (Grass carp, Silver carp, Big head carp, and Common carp). No significant differences were found between the chemical composition indices (i.e. protein, lipid, ash, and moisture) among cultivated cyprinids (P<0.05). In all of the four species, Palmitic acid (C16:0) and Oleic acid (C18:1 &omega;-9cis) were found to be the most abundant saturated and monounsaturated fatty acids, respectively. Oleic acid was significantly higher in common carp than other three species (P&le; 0.05). The most abundant PUFA were linoleic acid (C18:2 &omega;-6) in the common carp, decosahexaenoic acid (DHA, C22:6 &omega;-3) in grass carp and big head carp and arachidonic acid in silver carp. &omega;-3 fatty acid content in grass carp was higher (33.17±6.22) and had significant differences with silver carp (16.71±0.28) and common carp (9.26±5.1) (P&le;0.05). The results of this study also indicated that &omega;-3/&omega;-6 ratios were higher than 1, except for Common carp. &omega;-3/&omega;-6 ratios were 2.02±0.28, 1.66±0.29, 1.16±0.13 and 0.61±0.15 in Big head carp, Grass carp, Silver carpand Common carp, respectively. &omega;-3/&omega;-6ratio in all the species exceeded the eligible rates proposed by nutritionists. The Highest ratios of PUFA/SFA were observed in grass carp (2.23±0.29) (P&le;0.05) followed bythe bighead carp (1.41±0.12), silver carp (1.25±0.22) and common carp (0.98±0.23), respectively. These rates exceeded the eligible rate (0.45) recommended by HMSO for all the species in this research. It is noteworthy that all four species are of similar nutritious value. However, the Grass carp and Big head carp containhigher rates of PUFA, &omega;-3, &omega;-3/&omega;-6, PUFA/SFA, EPA+DHA than the Silver carp and Common carp.