نشریه آبزیان زینتی
سال دهم شماره 3 (پاییز 1402)

This study was designed with the aim of investigating the possibility of domestication and keeping Channa gachua in captive conditions in aquarium. For this purpose, 42 snakeheads were caught from their natural habitat located in the Kaju River in Sistan and Baluchistan province and transported in bags containing oxygen to the place of study in the ornamental fish research workshop of Islamic Azad University, Babol branch. For domestication in captivity, fishes were placed in seven different treatments (with three repetitions) in terms of tank types and maintenance conditions. During the investigation period, the water quality indices were controlled within the range of the natural biological conditions. The results showed that this fish has the ability to be domesticated and successfully kept in captivity, so that after three to four weeks, the behaviors showed reducing fear and stress. The most suitable conditions for keeping this fish in captivity include a tank volume of more than one hundred liters, the length and width of the tank respectively at least one hundred and forty centimeters, water depth of at least thirty centimeters, soft sand bed, the presence of shelters, water temperature of 24 to 26 degrees Celsius and daily change of 10% of tank water were detected. The fish started feeding on the fifth day after being kept in aquarium conditions, so that the nutritional preference was live baits, followed by sea shrimp. The one-year keeping of this fish without mortality in aquarium conditions showed that this Iranian native fish has the ability to adapt well to the captivity conditions and it can be introduced as a suitable replacement for similar imported non-native species in the ornamental fish industry.

The pollution of waters with low concentrations of environmental pollutants has attracted the scientific community's attention for several decades. It has become a significant challenge that addresses whether ecological concentrations of such compounds can disrupt the physiological function of organisms in aquatic ecosystems. In this regard, the present study evaluated the effect of feeding with Lactobacillus roteri and long-term exposure to naproxen on histopathology changes in zebrafish. In this study, the fish were fed with essential diet (TN, C) and probiotic (TP, TPN) (with a concentration of 1.5 × 108 CFU/ml) for 60 days, and at the same time, they were exposed to naproxen with a concentration of 100 μg/L (TN, TPN). Sampling was done to check intestinal morphology and histopathological changes of intestinal, liver, and kidney tissues on the 30th and 60th days of the test. The results showed a significant increase in the length and width of the villi and the number of goblet cells in the intestine in fish fed with probiotics. Also, due to exposure to naproxen, histopathological lesions such as villus corruption, vacuolization, necrosis, and hyperemia were reported in fish intestines. In the liver, the observed tissue complications included atrophy, fatty change, necrosis, thinning of the sinusoid, dark granules, blood occlusion, bleeding, and edema. Tubular necrosis, glomerular necrosis, hyperemia, infiltration of edematous cells, expansion of Bowman's space, and nephrocalcinosis were observed in kidney tissue. The remarkable thing was that in all three studied tissues, the destructive effect of the complications was reduced in the fish fed with probiotics. According to the results obtained in this study and the continuous increase in the consumption and release of drugs in aquatic environments, using Lactobacillus roteri probiotic supplement in aquaculture farms that use polluted water is recommended to improve fish health. As observed in this study, long-term exposure to low drug concentrations also causes tissue damage, resulting in significant economic losses.

The present research conducted within 8 weeks, aimed at examining the impacts of white worm (Enchytaerus albidus) on the growth function of Goldfish fry (Carassius auratus). Therefore, the effects of mixed experimental diet A (30% white worm/ 70% dry feed) and the control diet B (100% dry feed) on Goldfish fries (150±2.21mg) were determined in two treatments and three replicates. At the end of feeding phase, weight gain percentage (%), daily growth (%), daily weight gain (mg), FCR, protein efficiency (g) and SGR (%) were calculated in both groups. The results revealed that all growth related indices in the fries fed with mixed diets stood higher than those of in the control .(P≤0.05). The study also showed that the inclusion of white worm (Enchytaerus albidus) in the diet of Goldfish fries improved their weight gain.

With the expansion of the ornamental fish industry, the cultivation of these fish has grown significantly in recent decades, and the need for intensive and super-intensive aquaculture methods is felt more than ever. Various stressors such as transportation, high density, manipulation, and poor nutrition can have a negative impact on the immune system of fish and increase the power and ability of pathogenic agents. The use of medicinal plants, due to their low side effects, low cost, and easy accessibility, is considered a suitable alternative to chemical methods in controlling stress and fish diseases. Researchers worldwide are working to strengthen the immune system of fish to combat diseases. This study examines how various stressors are created in fish and how medicinal plants, as immune stimulants, can be effective in controlling stress and improving their health.

Nutrients in wastewater enrich the environment and cause environmental problems in aquatic environments. Conventional wastewater treatment systems are not capable of removing phosphorus effectively.  The  entry  of  phosphorus  into  water  resources  leads  to  the  formation  of  an Eutrophication  phenomenon. Micro-algae have been more effective among the various methods used for the removing of nutrients from wastewater. Wastewater biological-treatment using algae to eliminate nitrogen and phosphor and produce oxygen for aerobic bacteria is a new trend that has drawn a great deal of attention. Using sunlight, microalgae consume nutrients in wastewater and convert them into useful biomasses. Wastewater biological-treatment using microalgae was studied. Treatment efficiency of micro-algae depends on the species, algae mass concentration, aeration level, and the optimal time to maximize algae activity on wastewater.

Today, pistachio is a strategic product in the agricultural sector. Waste produced in the pistachio processing sector is considered as an important environmental problem. The presence of anti-nutritional compounds such as phenolic compounds and tannins has created difficult the use of this waste. Dietary supplements containing pistachio green shell extract reduced the stress of manipulating common carp. In general, it seems that by identifying and optimizing the appropriate methods of processing green pistachio shells such as enzymatic hydrolysis, fermentation and extraction, valuable compounds can be produced that can be used as a dietary supplement, growth stimulant and immunostimulant in aquafeeds.