فصلنامه تغذیه آبزیان
سال نهم شماره 3 (پیاپی 25، پاییز 1402)

Due to the side effects of chemical drugs, in recent years, the use of herbal medicines and their compounds in fish has been widely considered. The use of medicinal plants and their derivatives can stimulate feed consumption, increase daily weight, feed conversion ratio, increase shelf life, improve the health and function of the digestive system, minimize or mitigate the effects of stress on fish. Lemon herbena (Aloysia triphylla) is a member of Verbenaceae family. This plant is endemic to South America and can growth in other areas, such as Iran. This study was performed to evaluate the effect of Aloysia triphylla extract on anaesthesia, some water quality parameters, and haematology in juveniles rainbow trout, Oncorhynchus mykiss with average weight of 7 ± 0.42 g after transport.

The experiment was divided in three steps: 1: the anesthesia induction with Aloysia triphylla: 0 (control), 25, 50, 100, 200, and 400 μL/L; 2: transport for 4 h with the fish separated into three groups: control and two concentrations of A. triphylla: 12.5 and 25 μL/L; and, 3: determination of the ventilatory frequency in fish exposed to A. triphylla at 12.5 or 25 μL/L.

The results showed that the elevated concentration of A. triphylla proportionally decreased the time required for sedation and anesthesia induction and upraised the recovery time. After transport, lower blood serum glucose and cortisol and higher total protein, albumin, non-ionized ammonia, and dissolved oxygen levels in water were observed in fish exposed to 12.5 and 25 μL/L of the extract (p<0.05). By increasing the exposure time to A. triphylla, lower ventilatory frequency was found in fish exposed to 25 μL/L of extract (p<0.05).

In general, these results indicated that A. triphylla may have sedative and anesthetic effects on rainbow trout. Finally, it can be used to reduce the negative effects of stress caused by fish manipulation and transportation.

Nowadays, Spirulina algae is considered as a food supplement and even a healthy and useful food for human and is available in different forms such as powder, tablets, chips, etc. In addition to human consumption, Spirulina is used in aquaculture for feeding the larval stages of crustaceans and some other types of aquatic animals, to prepare livestock and poultry feed, and for cosmetic and industrial purposes. This study was carried out to evaluate the water capacity of the country's first deep aquifer well located in the Seistan region for the cultivation of Spirulina platensis.

Six treatments including deep aquifer well water with high salinity of 25, 12.5, and 5 ppt (Seistan deep aquifer well without changing salinity, deep water diluted with distilled water to 12.5 ppt salinity and 5 ppt) and tap water with high salinity of 25, 12.5 and 5 (prepared from Urmia Lake salt) were prepared. Spirulina algae was cultivated under standard conditions including temperature 30 ± 2 °C, light 37 µmol/m2/s; 16 hours light and 8 hours darkness for 21 days. At the end of the test period, the growth indicators and pigment concentration of the produced algae were measured, and by comparing the data obtained in different treatments, the ability of deep aquifer well water to grow Spirulina algae was determined.

The results showed that the highest biomass was obtained in the treatment of tap water and Urmia salt (2.91 ± 0.14 g/L) and the growth rate in the treatments containing deep aquifer water was lower than the other treatments.

The cultivation of Spirulina in the water of deep well (No. 1 Seistan) has a low efficiency compared to tap water, and it is necessary to modify and change its composition in some way so that Spirulina can be cultivated in with proper efficiency. 

One of the vital activities in the economic and environmental sector of the country is fish farming, which requires precise management for optimal efficiency and profitability. The distribution and timing of feeding are crucial aspects influencing the productivity and profitability of fish farming. In this regard, an intelligent system has been designed to automatically distribute the fish feed and provide an ideal schedule for fish nutrition. This system utilizes advanced technologies such as programmable control systems and precise distribution mechanisms to improve issues related to manual fish feeding. By the Arduino output components, the system injects feed into the aquaculture environment using mechanisms like servo motors. Additionally, the system has the capability to adjust the feeding schedule based on the nutritional needs of the fish, enhancing efficiency and minimizing the need for human intervention. This system assists fish farm managers in automating and efficiently managing the feeding operations, ultimately leading to improvements in the quality and quantity of their fish production.

The main components of the fish feed distribution and scheduling system consist of three essential elements: the Arduino Uno board, serving as a programmable platform; a servo motor with a single output shaft capable of positioning itself at a specific angle by receiving encoded signals; and a feeder, functioning as a storage and dispensing container for fish feed in the aquaculture system. The system operates by the Arduino board, utilizing pre-stored code, and making decisions based on predetermined time intervals between feeding sessions. These decisions include the timing and quantity of the feed, planned according to the fish type. In this system, at the specified time, the Arduino board sends a command to activate the servo motor. Upon activation, the gears of the servo motor rotate in four different positions, determined by the set time for the feeding session, causing the feeder connected to the motor to rotate. Consequently, the feed is uniformly distributed across the pond's surface.

In the realm of fish farming, one of the main challenges is the efficient and effective management of fish nutrition. Traditional methods of nutritional management, reliant on human labor, result in human errors and uneven food distribution, jeopardizing the health and growth of fish. These methods require time-consuming planning and can lead to issues such as water pollution, disease outbreaks, and increased costs due to overfeeding or underfeeding. To address these challenges, this study proposes an intelligent feeding and scheduling system using the Arduino microcontroller. This automated system offers balanced food distribution, precise timing and frequency of feeding, and control over the amount of consumed food. By setting accurate feeding times based on fish type and preventing food wastage, the system enhances the performance of fish feeding. Leveraging its strengths, including cost-effectiveness, high precision in feeding, optimal management of feed rations, and easy accessibility, this system is practically applicable in fish farms and ponds.

Based on the results of the present study, the intelligent fish-feeding device can bring significant improvements in nutritional efficiency, growth, and health of fish and enhances the performance of fish-feeding systems, contributing to the improvement of fish farming conditions and increasing profitability in the aquaculture industry.

Nutrition plays an important role in the functioning of the immune system and resistance to diseases. As a result, feeding and nutritional management are very sensitive and important. Nowadays, the use of substances that stimulate immunity and growth in the diet of aquatic animals is very important. The main reason for using these stimulants is their benefits, which include increasing growth, reducing food loss, increasing production, and obtaining a high-quality product. On the other hand, immune stimulants are added as supplements to the diet of aquatic animals and are used to prevent disease and improve the food conversion ratio. Seaweeds have high quantity of vitamins, minerals, protein, carotenoids, fiber, and essential fatty acids. In addition to being used as food, algae can have industrial, cosmetic, and medical uses. Algae have great economic importance due to having valuable polysaccharides such as agar, carrageenan, and alginate. Studies have shown that the use of dried algae as an immune stimulant in the aquaculture industry improves the physiological responses of fish to stress and disease, and as an immune stimulant in aquaculture, they increase growth, food efficiency, and biochemical quality of carcasses in various aquatic animals. The genus Gracilaria from the family Gracilariaceae is the largest genus from the Rhodophyta branch. They have a wide distribution worldwide and have been seen in polar, equatorial, and Mediterranean regions. However, there are limited studies regarding the use of Gracilaria gracilis algae powder in aquaculture. Considering the importance of common carp as one of the most important aquaculture species, the present study aims to investigate using different levels of G. gracilis algae powder in the diet and its effect on growth performance as well as some serum and skin mucus parameters in common carp.

This research was conducted for seven weeks in Shahid Nasser Fazli Barabadi Aquaculture Lab of Gorgan University of Agricultural Sciences and Natural Resources, Gorgan, Iran. In this experiment, common carp fry with an average weight of 19 g was used. The fish were adapted for two weeks and then kept in 12 fiberglass tanks (4 treatments 0, 0.25, 0.5 and 1% G. gracilis powder) with a density of 15 fish. The added ingredient in the diet was G. gracilis powder, supplied from South Iran. In this experiment, the basal diet was commercial extruded food size FFC from Faradaneh Company, Shahrekord, Iran and then the required amounts of G. gracilis algae (2.5, 5, and 10 g/kg) were mixed with the ingredients and made into the pellets. To investigate growth factors, the length and weight of all fish were measured. Fish mucus samples and blood samples were also collected. Data analysis and determination of significant levels were performed using SPSS 16 software and Duncan's statistical test with a confidence level of 95% and One-Way ANOVA test.

This research showed that the weight at the end of the period, the specific growth rate, and the food conversion ratio were not significantly different between the treatments containing red algae powder and the control group (p>0.05). Statistical analysis of the results showed no significant difference between the serum total immunoglobulin and total protein levels in the treatments fed with G. gracilis powder and the control group (p>0.05). The same results were noticed in case of skin mucus total immunoglobulin and total protein levels (p>0.05)

The results showed that adding G. gracilis powder (0.25, 0.5 and 1%) has no significant effect on growth and immune indices compared to the control group. The effect of adding herbal supplements to the diet on growth performance differs according to factors such as appropriate concentration, diet composition, and rearing management. Also, fish species, life stages, and experimental conditions are effective on growth performance results. The lack of significant difference between different levels of G. gracilis powder and the control group may be related to these reasons.

Dietary Selenium (Se) is vital for the growth and immune system of fish. The most important action of Se biological functions comes from several specific selenoproteins, some of which are involved in thyroid hormone metabolism, while others play an antioxidant defence role. Se as a nutritional element is obtained in the aquatic environment from two main sources: feed and fertilizer. Fish species absorb dietary Se in various forms, such as organic and inorganic. It should be used in the correct dosage and anything above this can have negative consequences. As for Se in the diet of fish, there are a few different forms commonly used as inorganic, such as Na2SeO3 or sodium selenite. Organic forms of dietary Se also include selenomethionine (SeMet) and selenocysteine (SeCyst). This study was performed to evaluate the effect of different sources of Se on growth performance, activity of antioxidant enzymes and thyroid hormones in rainbow trout.Organic Se (Se methionine), mineral Se (sodium selenite) and nanoselenium were added to the basal diet at a rate of 0.3 mg/kg. Basal food without Se compounds was used as a control treatment. Fish with an average weight of 29.25 ± 1.70 g were fed with experimental diets for 8 weeks. The fish were fed twice a day (at 9:00 AM and 2:00 PM) at the rate of 4% of their biomass. The results showed that selenium nanoparticles had no significant effect on growth indices compared to organic and inorganic forms (p<0.05). The activities of superoxide dismutase and catalase enzymes in treatments containing different forms of Se was significantly higher than in the control (p<0.05). The level of malondialdehyde in the liver of fish fed the diet containing sodium selenite was significantly lower than the other experimental treatments (p<0.05). The amount of triiodothyronine in treatments containing selenomethionine and Se nanoparticles was significantly higher than in the control group (p<0.05), which may be due to the stimulation of thyroid stimulating hormone. Thyroxine was not significantly different in fish fed with different forms of Se and in control (p>0.05). In general, using organic, mineral and nanoselenium sources with a concentration of 0.3 mg/kg of diet has strengthened the antioxidant status of rainbow trout fry, and also through the metabolism of triiodothyronine, it has improved the function of the thyroid gland.

The Caspian Kutum (Rutilus frisii) is a unique species of bony fish native to the Iranian coastal of the Caspian Sea, which can be a suitable fish for introduction to the aquaculture industry in Iran. Considering its marketability, commercial importance and high nutritional value, the Iranian Fisheries Research Institute, aimed to carry out an experimental study with the aim of increasing production and supplies, reducing fishing pressure and protecting its natural stocks in the Caspian Sea and finally, introducing as a new and strategic species to the country's aquaculture industries.

In this study, the growth performance and survival rate of cultured Kutum fry, with an initial average weight of 1.78 ± 0.66 g, were evaluated in two different densities: 25 and 50 fish/m2, for a period of 110 days in some concrete channel ponds with an approximate volume of 8 m3. The ponds received a constant water flow from an agricultural irrigation channel at the Restoration and Protection of Fish Genetic Resources of Shahid Ansari Center, Rasht, Iran.

The growth rate showed a significant inverse relationship with density in the experimental treatments (p<0.05), with average weight gain of 1364.84 ± 16.19 and 653.82 ± 44.29 g in the treatments 1 and 2, respectively. The food conversion ratio exhibited a direct relationship with density, displaying a significant difference with averages of 1.93 ± 0.13 in low- and 5.41 ± 0.56 in high-density treatments. Also, the results indicated that increased density led to a significant drop in body length gain indices, specific growth rate, and daily growth rate (p<0.05). There was a significant difference between treatments 1 and 2 in terms of survival rate at the end of the rearing period, with the values of 84.62 ± 3.52% and 77.95 ± 1.35%, respectively.

In general, the results of this study confirmed that the rearing of Kutum fry at a density of 25 fish/m3 in concrete ponds with freshwater is more suitable to achieve better performance.