The effect of Artemia urmiana nauplii enriched with flaxseed oil on growth performance, survival and fatty acid composition of SEVERUM, CICHLASOMA SEVERUM, larvae (0.3 mg initial weight) was investigated through a completely randomized block design with two treatments, viz., (1) larvae fed with plain nauplii, (2) larvae fed with nauplii enriched with flaxseed oil, in three replications. Results of the first biometry (day 18th), showed a significantly higher survival rate in treatment 1 (81.87±0.29%) than treatment 2 (68.83±1.62%) (P<0.05), but there were no significant differences in the specific growth rates, the average weight and length gains between treatments (P>0.05). At the end of the second period of the experiment (day 36th), significant differences in growth performance and survival rate was recorded between treatment 1 (97.82±1.09%) and treatment 2 (91.16±1.34%) (P>0.05). The larvae was also found to convert n-3fatty acids to EPA and DHA.

This investigation with headline "Effect of using enriched Artemia urmiana with highly unsaturated fatty acid and vitamin C on the fecundity of CICHLASOMA SEVERUM, has done in ornamental fish farm in a four-month period. During this research, fecundity rate, fertilization rate, hatching rate, larvae survival factors and the between times among continuous spawning, and total time for eight spawning have been evaluated. For this purpose, six feeding treatments were applied to SEVERUM broodstock as follows: concentrate food with 40% crud protein (Control), concentrate food+nonenriched alive Artemia, nonenriched alive Artemia, enriched alive Artemia with unsaturated fatty acid, enriched alive Artemia with unsaturated fatty acid, 0.5 gr vitamin C and enriched alive Artemia with unsaturated fatty, and 1 gr vitamin C. In this research, SEVERUM broodstocks has been kept in aquarium with 50 liters water, in 28±1o, pH: 7.5-8.3, and hardness was less than 170 p.p.m. Feeding was 4 times a day which was started at 7a.m and ended at 11p.m. Results show that the treatment fed with enriched alive Artemia with fatty acid and 1gr vitamin C (treatment 6), average of 712 seeds, 99% fertilization rate, 98% hatching rate and 98% larvae survival showed significant difference comparing to the control group. The least time for 8 times spawning by 45 days and the lowest between times among continuous spawning with 5 days in average, observed in a treatment 6, which it difference has also been significant. In summary, it can be said that the decline of mean time, which is necessary for eight times spawning due to the use of live food, results to efficiency of hatcheries and fish farms and perfect use of a broodstock. In addition enrichment of live food increases the mean time significantly.

The SEVERUM (Heros severus Heckel, 1840) is basically known as one of the beautiful fish species of cichlidae of Amazon River, which is very common in our country for breeding and reproduction. The aim of this study was to investigate the external and internal parasitic infections of the ornamental SEVERUM in ornamental fish trade centers in the country. In the summer of 1403, a random sampling was carried out and a total of 100 SEVERUM fish with a length of 7 to 12 cm were collected from 10 ornamental fish centers. The fish were referred to the Ornamental Fish Clinic of the Faculty of Veterinary Medicine, University of Tehran in fish carrying bags with the same water as the sampling site. In order to investigate the parasitic infection, wet smears were prepared from external organs (such as skin and gills) and then examined under a light microscope. Then, the fish were euthanized and necropsied under sterile condition. The bacterial culture result was negative. internal organs were also investigated for parasitic infestations. In the examination of the skin and gills, parasitic infection with 3 different genera including Trichodina, Ichthyophthirius multifiliis and Ancyrocephalus were observed. Also, in the microscopic examination of the intestine, infection with the protozoan parasite Hexamita, eggs and parasites of the nematode Capillaria, were observed. Considering the potential of some of the mentioned parasites in causing extensive losses, accurate and timely diagnosis of various infections caused by protozoa, monogeneans, cestodes and nematodes in ornamental fish including cichlids can be of great importance in preventing the occurrence of diseases and losses in these fish.

The aim of this study was improving antioxidant defense system and monitoring some plasma biochemical parameters of parrot fish fed on diet enriched with astaxanthin alone or in combination with bile salt after exposure to water-born silver nanoparticles (AgNPs). 200 parrot fish were randomly distributed in three different treatments as control, astaxanthin and astaxanthin-bile salt. The fish were fed for 90 days and then subjected to AgNPs 250 μ g/L for five days and some plasma biochemical parameters were measured before and after AgNPs stress. The results showed that feeding fish with diet enriched with astaxanthin could cause significant reduction in the plasma levels of all studied oxidative enzymes in comparison to the other groups (P<0. 05). AgNPs caused significant elevation in the levels of plasma oxidative enzymes in the control while such elevations were not visible in fish fed on astaxanthin (P>0. 05). At the end of feeding trail, day 90 th, plasma levels of hepatic enzymes, asparat transaminase and alanin transaminase were significantly lower in the astaxanthin-bile salt group (P<0. 05); after AgNPs stress, the levels of the mentioned enzymes were significantly reduced in groups of control and astaxanthin, while such reductions were not observed in the group fed on astaxanthin-bile salt diet (P>0. 05). The results of this study showed that astaxanthin alone or in combination with bile salt could improve some plasma oxidative and biochemical parameters of parrot fish when the fish were subjected to AgNPs. The positive effect of bile salt on astaxanthin function was observed on some parameters.

This study investigated the effects of mate switching on the reproductive performance of the SEVERUM cichlid, Herosseverus, by advancing the egg and larval production in hatcheries. Two reproductive tactic treatments of "monogamous pair" and "mate switching" were used for evaluating 4 reproductive traits of egg production, hatching rate, spawning intervals, and starvation tolerance of the larvae in 6 spawning activities. The number of eggs was not significantly different between the two reproductive tactic treatments in the 6 spawning activities, but the spawning intervals, hatching rate, and survival activity index were all significantly different. Daily average egg and larval production in the mate switching treatment were estimated to be 87.3 eggs and 43.1 larvae per pair of fish, respectively, which was 2.89 times and 1.99 times of those in the monogamous pair treatment, who produced about 30.2 eggs and 21.6 larvae per pair. Our results clearly showed that the reproductive tactic of mate switching is a suitable method for increasing the egg and larval production rate of the SEVERUM cichlid.

This study was conducted to investigate the effects of dietary betaine on fecundity, fertilization, hatching, larvae survival rates and interval times among continuous spawning in the Golden SEVERUM, Heros severus. For this purpose, three experimental diet treatments were applied to SEVERUM brood stocks as follow: an ornamental commercial diet without betaine (control diet), the commercial diet with 5g betaine per kg food (treatment 2) and the commercial diet with 10g betaine per kg food (treatment 3). Four replicates were used in this trial. In this study, 12 pairs of spawning SEVERUM fish has been kept in 12 aquariums with 50 liters volume, in 28 ± 1° C. Feeding were two times a day. The highest fecundity with average of 655. 4 eggs were observed in treatment 3 and the highest hatching rate and larval survival rate respectively 98. 79 and 94. 58 were observed in treatment 2 which were significantly different from the control (P≤ 0. 05). The shortest interval times between continuous spawning with average of 7. 31 days was observed in treatment fed with 5g betaine per kilogram diet which was significantly different from the other treatments. In summary, it can be concluded that using betaine with 5 g per kg diet can make a positive increasing in reproductive performance in SEVERUM fish.

This study was aimed to improve Parrot fish fitness, respecting antioxidant defense system and plasma biochemical parameters affected by starvation. 198 parrot fish (average weight 25. 5± 6. 2 g and length 6. 34± 0. 43 cm) were randomly distributed in three different treatments, including control (basic diet), astaxanthin (diet enriched with 4g/kg astaxanthin) and astaxanthin-bile salt treatment (diet enriched with 4g/kg astaxanthin and 1200 mg/kg bile salt). The fish were fed for 90 days and then subjected to starvation for 7 days. Bleeding was done at the end of feeding period (before starvation stress) and after starvation phase and some plasma oxidative stress enzymes and blood biochemical parameters were analyzed. Results showed that feeding fish with astaxanthin alone, can reduce the levels of oxidative stress enzymes in fish in comparison to the control at the end of the feeding period while reduced levels of liver enzymes such as asparat aminotransferase and alanine aminotransferase were only observed in fish fed on diet enriched with astaxanthin-bile salt (P<0. 05). Starvation caused significant elevation of plasma oxidative stress enzymes in the control group (P<0. 05), while such changes were not observed in fish fed on astaxanthin and/or astaxanthin-bile salt treatments (P>0. 05). In general, it can be concluded that starvation can cause plasma oxidative stress enzymes elevation, plasma total protein and liver enzymes reduction in parrot fish; nevertheless, by dietary astaxanthin supplementation alone or in combination with bile salt, the negative effects of starvation on parrot fish, at least for some physiological parameters, can minimized.

This study aimed to investigate the effects of water-born silver nanoparticles (AgNPs) on gill histopathological alternation of Parrot and the possible protective effects of diet enriched with astaxanthin alone or in combination with bile salt.200 Parrot fishes (average weight 25.5±6.2) were randomly distributed in three different groups: control (basic diet), astaxanthin alone (4g/kg) or in combination with bile salt (1200 mg/kg). The fish were fedfor 90 days and then subjected to AgNPs, 250 mg/L for 5 days. The silver bioaccumulation and gill histopathology analysis were done before and after exposure period. The results showed significant increase in silver concentration in the gill tissues of the control group after AgNPs exposure (P<0.05), while feeding fish on diet enriched with astaxanthin alone or in combination with bile salt did not show such elevation in silver concentration (P>0.05). After exposure to AgNPs, different gill histopathological alterations such as hyperplasia, hypertrophy, looping, necrosis and fusion were observed in fish from all treated groups, although the intensity of them were significantly lower in the groups of fish fed on astaxanthin alone or in combination with bile salt, comparison to the control group. In general, it can be concluded that diet enriched with astaxanthin alone or in combination with bile salt as antioxidant supplement can reduce the harmful effects of AgNPs on the gills.