Susceptibility of Goldfish to Cyprinid Herpesvirus 2 (CyHV-2) SH01 Isolated from Cultured Crucian Carp

Cyprinid herpesvirus 2 (CyHV-2), a member of the Alloherpesviridae family belonging to the genus Cyprinivirus, is a fatal contagious aquatic pathogen that affects goldfish (Carassius auratus) and crucian carp (Carassius carassius). Although crucian carp and goldfish belong to the genus Carassius, it is unclear whether they are susceptible to the same CyHV-2 isolate. In addition, the origin of the crucian carp-derived CyHV-2 virus isolate remains unclear. CyHV-2 SH01 was isolated during herpesviral hematopoietic necrosis disease (HVHN) outbreaks in crucian carp at a local fish farm near Shanghai. CyHV-2 SH01 was confirmed by PCR and Western blot analysis of kidney, spleen, muscle, and blood tissue from the diseased crucian carp. Moreover, histopathological and ultra-pathological analyses revealed pathological changes characteristic of CyHV-2 SH01 infection in the tissues of the diseased crucian carp. In the present study, goldfish and crucian carp were challenged with CyHV-2 SH01 to elucidate viral virulence. We found that CyHV-2 SH01 could cause rapid and fatal disease progression in goldfish and crucian carp 24 h post-injection at 28 °C. Experimental infection of goldfish by injection indicated that the average virus titer in the kidney of the goldfish was 103.47 to 103.59 copies/mg. In addition, tissues exhibited the most prominent histopathological changes (cellular wrinkling and shrinkage, cytoplasmic vacuolation, fusion of the gill lamellae, and hepatic congestion) in CyHV-2 SH01-infected goldfish and crucian carp. Thus, crucian carp and goldfish showed a high sensitivity, with typical symptoms, to HVHN disease caused by CyHV-2 SH01.

Transfer of Cobalt Nanoparticles in a Simplified Food Web: From Algae to Zooplankton to Fish

Cobalt (Co) nanoparticles (NPs) may be diffusely dispersed into natural ecosystems from various anthropogenic sources such as traffic settings and eventually end up in aquatic systems. As environmentally dispersed Co NPs may be transferred through an aquatic food web, this study investigated this transfer from algae (Scendesmus sp.) to zooplankton (Daphnia magna) to fish (Crucian carp, Carassius carassius). Effects of interactions between naturally excreted biomolecules from D. magna and Co NPs were investigated from an environmental fate perspective. ATR-FTIR measurements showed the adsorption of both algae constituents and excreted biomolecules onto the Co NPs. Less than 5% of the Co NPs formed heteroagglomerates with algae, partly an effect of both agglomeration and settling of the Co NPs. The presence of excreted biomolecules in the solution did not affect the extent of heteroagglomeration. Despite the low extent of heteroagglomeration between Co NPs and algae, the Co NPs were transferred to the next trophic level (D. magna). The Co uptake in D. magna was 300 times larger than the control samples (without Co NP), which were not influenced by the addition of excreted biomolecules to the solution. Significant uptake of Co was observed in the intestine of the fish feeding on D. magna containing Co NPs. No bioaccumulation of Co was observed in the fish. Moreover, 10–20% of the transferred Co NP mass was dissolved after 24 h in the simulated gut solution of the zooplankton (pH 7), and 50–60% was dissolved in the simulated gut solution of the fish (pH 4). The results elucidate that Co NPs gain different properties upon trophic transfer in the food web. Risk assessments should hence be conducted on transformed and weathered NPs rather than on pristine particles.

The Metabolomic Response of Crucian Carp (Carassius carassius) to Anoxia and Reoxygenation Differs between Tissues and Hints at Uncharacterized Survival Strategies

The anoxia-tolerant crucian carp (Carassius carassius) has been studied in detail for numerous years, with particular focus on unravelling the underlying physiological mechanisms of anoxia tolerance. However, relatively little work has been focused on what occurs beyond anoxia, and often the focus is a single organ or tissue type. In this study, we quantified more than 100 metabolites by capillary electrophoresis-mass spectrometry (CE-MS) in brain, heart, liver, and blood plasma from four experimental groups, being normoxic (control) fish, anoxia-exposed fish, and two groups that had been exposed to anoxia followed by reoxygenation for either 3 h or 24 h. The heart, which maintains cardiac output during anoxia, unexpectedly, was slower to recover compared to the brain and liver, mainly due to a slower return to control concentrations of the energy-carrying compounds ATP, GTP, and phosphocreatine. Crucian carp accumulated amino acids in most tissues, and also surprisingly high levels of succinate in all tissues investigated during anoxia. Purine catabolism was enhanced, leading to accumulation of uric acid during anoxia and increasing urea formation that continued into 24 h of reoxygenation. These tissue-specific differences in accumulation and distribution of the metabolites may indicate an intricate system of transport between tissues, opening for new avenues of investigation of possible mechanisms aimed at reducing the generation of reactive oxygen species (ROS) and resultant tissue damage during reoxygenation.

Differences in some cranial bones between two Cyprinidae species, Common carp Cyprinus carpio (Linnaeus, 1758) and Crucian Carp Carassius carassius (Linnaeus, 1758) Collected from Tigris River, Iraq

The present study attempts to identify some of the differences between the skull bones of two species Cyprinus carpio and Carassius carassius, which belong to the Cyprinidae family. The study is a taxonomic diagnostic study between the two species which are considered local fish abundant in the Iraqi aquatic environment

Extracorporeal acidic predigestion of commercial dry diets can reduce the incidence of body deformities in the stomachless fish crucian carp (Carassius carassius L.)

The aim of the present study was to test the hypothesis that predigesting commercial dry diets for fish with hydrochloric acid (HCl) can contribute to the reduction of the incidence of body deformities in a stomachless cyprinid species intensively reared under controlled conditions. Two different dry diets (Carpco Crumble by Coppens International and Aller Futura by Aller Aqua), their respective variants modified with HCl, and frozen larval chironomids (control diet) were fed as sole food sources to juvenile Carassius carassius in a recirculating aquaculture system at 25°C for 60 days. At the end of the experiment, visible body deformities occurred exclusively in the groups fed dry diets. The shares of deformities were significantly lower in fish groups fed the modified diets (6.1–13.2%) as compared to those fed the original ones (74.0–87.0%). Fish in the latter groups had significantly the highest condition factor values, which indicated a possible phosphorus deficiency. As evidenced by our results, predigesting commercial dry diets with HCl can be a useful method to mitigate the problem of body deformities occurring in intensively fed cyprinid species.