Sustainable Aquaculture and Health Management Journal
Volume:5 Issue: 2, Summer and Autumn 2019

Ichthyophonus is a unicellular fish parasite with a range of hosts and therefore a lot of economic losses. In this study, Ichthyophonus infection was reported in diseased angelfish, Pterophyllum altum. Samples were provided from three angelfish referred to veterinary hospital and examined by routine methods. The fish were lethargic with mild symptoms of chronic disease. According to a spherical shape and globular morphology of agent (characteristic spores surrounded by a thick fibrous membrane seen in squash preparations made from heart and spleen) and further histopathology and culture results, agent was described as Ichthyophonus hoferi. The result showed two main phases in the life of infecting parasites, 'active' and 'passive', the passive form is prone to convert to active. As another result, white-cream cysts were seen in infected organs. The most obvious macroscopic symptom of ichthyophonosis in angelfish was the spots on the skin and nodules in the heart. The cysts were filled with schizonts that were surrounded by fibroblasts, collagen fibers and many eosinophilic inflammatory cells. In the next step, tissue samples were also separated and incubated into Minimum Essential Medium (MEM) to see the germination of Ichthyophonus hoferi. This test was suggested for recognizing Ichthyophonus from Mycobacterial infections.

Administration of human anesthesia drugs in fish is mainly because of their high efficacy and availability as well as low price. In this study anesthetic effects of Ketamine and Acepromazine (0, 15 and 30 mg L-1) was evaluated in Shirbot (Tor grypus). Acepromazine concentrations prepared in 10 L containers in triplicates, then serial descending concentration of ketamine (for effective dose 20-400 mg L-1 and for lethal dose 320-900 mg L-1) were added to tank. Twelve fish were added to each container. Results analyzed with probit software and EC10, EC50 and EC90 as well as LC10, LC50 and LC90 of drugs in five minutes were measured. Results showed that no significant difference was seen in anesthesia efficacy, time of anesthesia induction and recovery time among groups (P>0.05), but lethal effects of Ketamine decreased significantly in Ketamin along with 15 mg L-1 Acepromazine (P<0.05). Then it can be concluded that Acepromazine increased the safety of Ketamine in Tor grypus at low doses.

Viral hemorrhagic septicemia virus (VHSV), Infectious hematopoietic necrosis virus (IHNV), and infectious pancreatic necrosis virus (IPNV) are documented as the most considerable viral pathogens in Rainbow trout (Onchorhynchus mykiss). This study aimed to evaluate the frequency of these pathogens in 65 farms with suspected clinical signs in northern Iran from March 2016 to February 2018. Logistic regression analysis used to assess the effect of several determinant factors on the occurrence of these pathogens. In total, 19 (29.23%) farms were positive by a reverse transcription-polymerase chain reaction (RT-PCR). The frequency of VHSV, IHNV, and IPNV was reported 18.5%, 6.2%, and 4.61%, respectively. The most affected farms (78.95%) used river water. Furthermore, our results revealed that using river water raised the chances of viral disease by 5 times (OR= 5.02; P= 0.01). Thus, using river water was a risk factor for the occurrence of viral pathogens. From four weight groups (A to D); fishes in groups A (fish < 1 gr) and B (1 to 20 gr) were more affected but not statistically significant (P>0.05). This study has provided insight into the frequency of these targeted viruses. Collectively, establishing routine rapid diagnostic programs and setting up basic educational practices can be valuable to design the prevention and control strategies.

Status of Chrysichthys nigrodigitatus, an economic important fish of the Gulf of Guinea was investigated over 24 months in Lagos Lagoon to know the state of well-being of the fish; for fisheries management, public health and food security. Ecological tools employed to determine some hydrodynamic status. Water analysis: temperature (°C), pH, dissolved oxygen (mg l-1), conductivity (μЅcm), depth (m), turbidity (m), and salinity (%0) were determined. Fish with mean standard length 18.90 ± 1.35 (cm) and mean weight range (201.59 ± 38.29) (g) were randomly collected and separated into sexes. Condition factor and regression analysis determined. Some heavy metal concentrations (Lead, Iron, Zinc Copper, and Chromium) levels were determined in fish tissues. No significant difference (P ≥ 0.05) occurred in water parameters from normal range using ANOVA. Sex ratio indicated higher male to female (40:32) which is nature specific. Morphometric measurement indicated female samples revealed negative allometric, but better condition factor (K) (2.86); while male revealed positive allometric and lower condition factor (K) (0.44) which is sex, reproduction and food availability specific; as robustness indicate state of well-being of the fish. Heavy metal values revealed slight accumulations. Results connoted fish species is relatively safe and of public health value.

An excellent alternative for chemical antimicrobial agents to prevent disease in the shrimp aquaculture is the application of effective probiotics. The present study was evaluated the effect of Bacillus vallismortis IS03 as a native probiotic, isolated from digestive tract of Litopenaeus vannamei on pathogenic Vibrio harveyi under in vitro and in vivo circumstances. Co-cultivation of V. harveyi and B. vallismortis showed significantly (P<0.05) decreased the growth of V. harveyi in the treatment groups compared to the control. Cell-free extracts of B. vallismortis IS03 exhibited more appropriate antibacterial effects on replication of V. harveyi. The highest and lowest inhibitory effects were respectively shown in108 and 106 CFU ml-1 of B. vallismortis IS03 cell-free extracts. The probiotic potential of B. vallismortis IS03 was assessed through the groups of control and the experiments 106, 107 and 108 CFU ml-1 salt water once every 3 days from zoea1 process to end point of the study. The probiotic potential of B. vallismortis IS03 was assessed through the groups of control and the experiments 106, 107 and 108 CFU ml-1 salt water once every 3 days from zoea1 process to end point of the study. Shrimp survival was determined after 10 days of challenge with V. harveyi  at 10 5 CFU ml-1 (for the first 5 days) and 10 7 CFU ml-1  (for the second 5 days).The cumulative mortality in the treatment with 108 CFU ml-1 of  B. vallismortis IS03 reached 11.88% compared to 40.63% in the control group. At the end of the trial, total bacterial counts on TSA, total vibrio on TCBS were significantly (P<0.05) lower in the 108 CFU ml-1 treatment group. Bacillus counts on MYP agar in the treatment groups were significantly (P<0.05) higher than the control, also total bacterial counts was lower in the treatment groups, while, no vibrio were grown in the muscle tissues of shrimp treated with probiotics. It is concluded that 108 CFU ml-1 of probiotic, B. vallismortis IS03 has antibacterial efficiency against pathogenic V. harveyi at in vitro and in vivo conditions.

The current study investigates the effect of gamma radiation (0, 1, 3, 5, 7 kGy) and vacuum packaging on shelf-life of silver carp surimi stored at 4 ºC based on variations in pH, peroxide value (PV), thiobarbituric acid (TBA), total volatile nitrogen bases (TVB-N), free fatty acids (FFA), colorimetric parameters (L*, a*, b*), total viable bacterial count (TVC) and textural profile analysis during 15 days. The results indicated that pH did not change with gamma radiation (P> 0.05). Results of oxidative index showed that PV and TBA in surimi reduced significantly with an increase in gamma radiation (P< 0.05) while their increased by increasing the storage time. Irradiation and the storage time significantly increased TVB-N content (P< 0.05). The increase the radiation dose (up to 7 kGy) and the storage time (up to 15 days) had a significant increasing effect on FFA in refrigerated surimi. Colorimetric evaluations demonstrated that after irradiation, samples had generally higher L*, a*, b* indices. Furthermore, increasing the radiation dose significantly reduced the total bacterial count in surimi samples (P< 0.05), but this parameter exhibited a significant increase (P< 0.05) with increasing storage time. Based on the textural profile analysis it was found that increasing radiation dose and storage time reduced the hardness and chewing ability indices. According to the microbiological and chemical results, the optimal storage time for surimi, compare to the control (0 kGy) treatment, was measured for 7 kGy treatment which could increase the storage time by 3 days compared to the control.