Ebrahim Najdegerami, Mehran Javaheri,
Volume 12, Issue 3 (11-2012)
Abstract
Light is one of the most important environmental factors in fish life. The effect of photoperiod on the growth performances and survival of rainbow trout (Oncorhynchus mykiss) larvae and fingerlings was investigated in two consecutive experiments. In both experiments fishes were exposed to four treatments (24L/0D, 16L/8D, 8L/16D, 0L/24D) (light: dark, L: D) in three replicates. The results of first experiment indicated that photoperiod affected on the growth performances in larval stage of rainbow trout. The best weight gain and specific growth rate was observed in 24L: 0D and 16L: 8D without significant differences between them and the lowest rates was achieved in 0L: 24D. Also in second experiment, the effect of photoperiod on the growth performances was significant difference and the highest growth rate and specific growth rate was observed in 8L: 16D and the lowest in 24L: 0D and 0L: 24D. Our results showed that the effect of photoperiod in rainbow trout depends to developmental stage and larvae unlike fingerlings have better growth in long light phases.
Volume 18, Issue 45 (6-2008)
Abstract
Malachite green is a carcinogen and mutagen material that is not permitted by FDA as a fungicide for edible fishes. Alvita(sodium di acetate), is a fungicide and bactericide material which is admitted by FDA.The research has been done by two methods: invivo and invitro. In invitro, at first the eggs that fungi attached them, cultured on SDA, then fungi colonies pured. At last, Mucor and Rhizopus were known by Slide culture and morphological analysed. In the second phase, Alvita was added to SDA in 1,5,10,15 and 20 g/lit concentration. Then pured colonies, cultured on SDA with 1,5,10,15 and 20 g/lit concentration of Alvita. After 48 hours and one week, samples were examined. In blank(without Alvita), the fungi colonies grew, but no colonies grew on other samples with 1,5,10,15 and 20 concentration of Alvita, then 1 g/lit was recognized as a minimal concentration that any colonies didn't grow on it. In invivo method(which has been done in Niyak farm), there were 5 traphs for trout culture, that one of them was blank, three of them contained Alvita, with 1 g/lit for 30 minutes, 1g/lit for 1 hour, 2 g/lit for 30 minutes and one of them contained malachite green with 2 mg/lit concentration for one hour. All of examinations were done in triplicate. The results of study analyzed by ANOVA, with 95% confidence limit and(P=0.265), to show, concentration of Alvita(1 g/lit), is the best alternative of malachite green, between examined concentration.
