The lethal concentration (LC50) of Zataria multiflora essential oil in fries of rainbow trout (Oncorhynchus mykiss)

This research was carried out to determine LC50 for Zataria multiflora essential oil in rainbow trout (Oncorhynchus mykiss) fries at 96 hours. In the process, we used the static O.E.C.D method for 180 rainbow trout fries weighing 5±1 grams in five treatments and one control with three replicates. During the experiments, the mean (±SD) of water temperature was kept at 16±1 C, dissolved oxygen (DO) was 7±0.2mg/l and pH was 8±0.4. We used 5- 25ppm of the essential oil and the results were analyzed using probit analysis procedure. The LC50 96h of Zataria multiflora essential oil was determined as 13.6ppm for rainbow trout (Oncorhynchus mykiss) fry. Based on the results, the useful maximum concentration of Zataria multiflora essential oil was less than 10ppm in rainbow trout fry. The results indicated a narrow therapeutic index for Zataria multiflore essential oil

Investigation of survival ratio and growth rate in offspring of Salmo trutta caspius

We investigated the survival ratio and the growth rate of offspring of Salmo tuna caspius produced from three groups of brood fish in Shahid Bahonar Rearing and Breeding Center in Klardasht in 2005. The three groups of brood fish belonged the early, mid, and late-migration period. The sampling was done randomly, and in each group 15 female and 5 male fish were included. After spawning and hatching, 22500 eggs were used in each group (3 treatments, repeated 9 times). The results showed no significant difference in the survival ratio of the egg and larva in the three groups of the brood fish in each stage of evolution up to two months after the start of active feeding (P>0.05). However, after the start of active feeding there was a significant difference (P 0.05). Based on the results, we suggest that the brood fish from the early migration period are more suitable for producing offspring and their offspring pass through the smoltification stage more rapidly. However, in terms of genetic diversity, it would be appropriate to use brood fish from all migration periods

A study of the anesthetic effect of Zataria multiflora Boiss (Labiatae) essence on Oncorhynchus mykiss and cultured Salmo trutta caspius

For the first time in the world, the effect of Zataria multiflora essence in concentrations of 50 and 100 ppm on Oncorhynchus mykiss fry weighing on average 15±2 g and cultured Salmo trutta caspius weighing on average 40±4 g was studied. The water temperature was 16-17 °C, dissolved oxygen was 7±0.2 and pH was 8 during the investigation. O. mykiss and S. trutta caspius reached complete sedation during an average time of 3 and 2 minutes respectively in the two concentrations. The mean balance and recovery time were 2 and 3 minutes respectively. Results showed that the sedation and recovery time are significantly different in the two species and with the two concentrations of the sedative (P<0.05). The research also showed that Z. multiflora essence has an anesthetic effect on the two species, but because of the unwanted severe irreparable breathing side effects and the accompanied body deformation of the two species, the essence is not suggested as an anesthetic for the fish. The essence is not recommended as a general anesthetic, but it may be used in 15-20ppm as a sedative during manipulation of the fish

Growth performance and age composition of Salmo trutta caspius in Iranian part of Caspian Sea

The aim of this project is to study the growth and age structure in the Caspian trout, comparison with other coldwater species and check the trend of these parameters in recent years. This study was conducted during 2013 till 2015. Totally, 43 specimens for back calculation and 101 specimens for biometrical study of the Caspian trout have been caught in two month period. Biometric parameters such as length, weight and age of the fish were recorded. Base on Back calculation method in 1393, the average length of fish at ages 1, 2 and 3 years old were 18.98 ± 3.5, 30.5 ± 7.24 and 41.7 ± 9.1 cm. So these age groups are under the adult age and don’t approaching to near the beach and rivers for spawning behavior. Therefore, these length groups cannot be observed in catch composition. The result showed, the mean of gonad weight in this fish was about 11 percent of total weight and number of eggs per gram of gonad calculated about 10.8 numbers. Minimum age and maximum age of this species determined 4 years and 7 years (mean = 5.6) and the most frequency allocated to 5 age group and the frequency of 6 and 7 years has been remarkable. The average length of salmon was 69.2 ± 6.2 cm (minimum 57 and maximum 81 cm) and the average weight was measured 3323 ± 677 g (2400 to 5600 g) in the catch composition. Growth parameters such as k, L_∞ and ø’ was measured 0.18, 104 cm and 3.289 respectively. The amount of b for relation length and weight was 2.9 which imply negative allometry. L_∞ and growth coefficient (K) on the Caspian trout were acceptable range, that it shows good growth the fish in the sea water. Most of the fishes were catched from Cheshmehkileh River. As at present Shilat uses just the broods of the Tonekaboon region for restocking of this species, we recommend using the broods of the western region separately for rehabilitation of the stocks of this region