https://japb.guilan.ac.ir/ Aquatic Physiology and Biotechnology en daily 1 Sun, 09 Nov 2025 00:00:00 +0330 Sun, 09 Nov 2025 00:00:00 +0330 https://japb.guilan.ac.ir/article_9190.html Common carp (Cyprinus carpio) is one of the most important warm water cultured fish species in the world. In Development of an sustainable aquaculture system requires year-round fry and fingerlings production of fish. Common carp in tropical and subtropical areas reach maturity at a young age and low weight. In this study, out-of-season common carp fingerligs were used compared to the conventional culture method. 4 ponds of 2 hectares were selected for cultivation.Common carp fingerlings from spring and off-season (autumn) reproductions were used for stocking in the rearing system with conventional density. The beginning of culture period in off-season and spring propagation was done in April and June, respectively. In this study, common carp fingerlings were cultured together with silver carp, big head carp, and rohu species. 6850 fingerling fish were stocked in two hectares. The composition of common carp, silver carp, big head carp, and rohu in off-season carp was 32, 23, 5, and 40%, respectively, with the initial weight of common carp in off-season breeding and spring breedingwas 20 and 6 grams, respectively. Sinking pellet food for common carp with a protein percentage of 26% was used to feed with twice a day. Water parameters were measured during the rearing period. Nutrition and growth parameters including specific growth ratio (SGR), food conversion ratio (FCR), weight gain percentage (WG), survival percentage (SVR), daily growth rate (FI), protein efficiency ratio (PER) were investigated, as well as economic indicators including economic conversion factor and profit index (P) calculated. The results showed that the growth and nutrition indicators did not show significant differences during the culture period. The food conversion rate in off-season carp was lower than the normal culture of spring breeding carp. Economic coefficient and profit index in off-season breeding compared to Spring carp showed a significant difference (P<0.05). The rearing period in common carp outside the season was shorter and they reached the desired weight in September, while in spring breeding carp, the breeding period was longer and they reached market weight at the end of autumn. The obtained results showed that the use of common carp in the off-season can contribute to increasing production and shortening the culture period. https://japb.guilan.ac.ir/article_9232.html In the marine environment, microorganisms colonize all surfaces, including various marine organisms such as macroalgae. These microorganisms associated with marine macroalgae represent a significant source of biologically active metabolites. Biofouling remains a persistent problem in the marine sector, necessitating effective control and cleaning strategies. The search for antifouling bacteria is essential to controlling biofouling, particularly given the environmental pollution associated with the use of toxic chemicals. In this study, four symbiotic bacteria were isolated and purified from Enteromorpha flexuosa macroalgae collected from the Oman Sea. Molecular identification of these bacteria, based on 16S rRNA gene sequence analysis, identified them as Bacillus zhangzhouensis strain Chabahar 1, Virgibacillus dokdonensis strain Chabahar 2, Micrococcus endophyticus strain Chabahar 3, and Bacillus subtilis strain Chabahar 4. These sequences were deposited in GenBank under the accession numbers OL472895, OL514166, OL514165, and OL514183, respectively. A phylogenetic tree was constructed to illustrate the kinship relationships among these bacteria. Ethanol extracts were prepared from these bacteria and screened for activity using the well diffusion method. However, these extracts did not exhibit any growth inhibitory effect. https://japb.guilan.ac.ir/article_9330.html In this research, the probiotic effects of Lactobacillus corvatus bacteria isolated from fish ponds were investigated for histopathological studies. For this purpose, white fish fry with an approximate weight of 8.05 ± 1.58 grams were randomly divided into six groups. The control group, the group with only Lactobacillus curvatus (10 8 Cfu/g), the group exposed to lead (12 mg), the group exposed to cadmium (4 mg), the group + Lactobacillus corvatus (10 8 Cfu/g with lead) and the cadmium group + Lactobacillus curvatus (10 8 Cfu/g with cadmium). Each treatment was done in three replicates. After adapting to the environmental conditions for 14 days, the treatments were kept for 56 days. After the mentioned period, the anesthetized fishes, the intestines and livers of the fishes were isolated, stored in Boen's solution and transferred to a specialized laboratory for histopathology tests. The results of microscopic tests showed that in the treatment containing lead and cadmium, hyperemia (low), the presence of blood cells in the lamina propria (lp), necrosis of enterocyte cells and microvilli and cell vacuoles were observed in the intestines of juvenile fish. Histopathological examination of liver tissue showed hyperemia and bleeding (high), cell necrosis (high) and cell vacuolation (low). After examining the liver and intestinal tissues of fishes exposed to heavy metals lead and cadmium compared to the treatments containing probiotics, the amount of tissue repair was observed in the treatment containing probiotics. Therefore, according to the results, a favorable effect on the liver tissue was observed at this stage. https://japb.guilan.ac.ir/article_9541.html Phycobiliproteins, a class of naturally occurring bioactive compounds derived from organisms such as red algae and cyanobacteria, have attracted considerable attention due to their diverse biological activities. The present study aimed to investigate the structural characteristics, spectral properties, and the free radical scavenging, antioxidant, and antimicrobial activities of two major phycobilipigments. These pigments were extracted from Spirulina platensis and Gracilaria gracilis, respectively. The extraction procedure involved repeated freeze–thaw cycles followed by ammonium sulfate precipitation and dialysis for partial purification. spectrophotometric analysis revealed maximum absorption peaks at 620 nm for phycocyanin and at 495 and 545 nm for phycoerythrin. SDS–PAGE analysis confirmed the presence of α and β subunits (18–20 kDa) and a γ subunit (31kDa). FTIR spectroscopy demonstrated the presence of characteristic biological functional groups, including the (amide I) band at 1644 cm⁻¹ and tetrapyrrolic structures.The DPPH assay verified the antioxidant capacity of both pigments. The free radical scavenging activity was 59% for phycoerythrin and 42% for phycocyanin. Disk diffusion assays demonstrated that both pigments exhibited antimicrobial activity against Staphylococcus aureus and Escherichia coli. Phycoerythrin showed the highest activity against Gram-positive bacteria, whereas phycocyanin exhibited greater inhibitory effects against Gram-negative bacteria. These findings highlight the significant potential of these pigments for pharmaceutical, industrial, and food applications. https://japb.guilan.ac.ir/article_9442.html This study aimed to investigate the effects of feeding zebrafish (Danio rerio) larvae with Artemia nauplii enriched with different levels of prebiotic Prodi 450, containing mannan-oligosaccharide and β-glucan, on growth performance and innate immune parameters. The experiment was conducted in two phases, including Artemia nauplii enrichment and zebrafish larval feeding for 14 days. Artemia nauplii were enriched with four levels of prebiotic including zero (P0), 50 (P50), 100 (P100), and 200 (P200) mg L⁻¹. Larvae with an initial mean weight of 46.08 ± 0.58 mg were reared under controlled conditions. Growth parameters including weight gain, body weight increase, specific growth rate, daily growth rate, feed efficiency, and survival rate were measured, and innate immune parameters including total protein, total immunoglobulin, and alkaline phosphatase activity were evaluated. The results showed that feeding larvae with prebiotic-enriched Artemia nauplii had no significant effect on final weight or survival rate (p>0.05); however, weight gain, daily growth rate, and feed efficiency in the P200 group were significantly higher than in P50 (p<0.05), although not significantly different from the other treatments (p>0.05). Specific growth rate and body weight increase were significantly higher in P0 and P200 compared to P50 (p<0.05), while innate immune parameters showed no significant differences among treatments (p>0.05). These findings suggest that prebiotics may enhance larval growth performance, possibly through regulation of gut microbiota and improving nutrient absorption, even within a short feeding period, whereas their effects on immune indices remain limited at the larval stage. Partial retention of prebiotics within Artemia tissues, as well as enrichment dose and duration, may influence final bioavailability. The nonlinear growth response may reflect complex metabolic and microbial interactions, suggesting the need for further research in this field.