Adult Koi Research Articles

Influence of antioxidants on the growth performance, gonadosomatic index and biochemical properties of gonad and fertilization success in koi carp (Cyprinus carpioL.)

Adult koi carp (Cyprinus carpio L.) were fed with feed supplemented with vitamin C at 200 mg/kg feed (T1), 400 mg/kg feed (T2) and 600 mg/kg feed (T3), and vitamin E at 200 mg/kg feed (T4), 400 mg/kg feed (T5) and 600 mg/kg feed (T6) at ad libitum for 60 days. Control (without vitamin inclusion) was also maintained. Observations were made on the growth performance, GSI and biochemical composition of gonads such as crude protein, crude fat, cholesterol and carotenoid once in 15 days. At the end of the experiment, fertilization was done to record the fertilization and hatching rate. The difference in the values was noticed among the male and female koi carp. Fish supplemented with vitamin E at 200 mg/kg feeexhibited higher growth in both male and female fish, and the fertilization rate and hatching rate were also higher in that group, and the values were significantly different (p < 0.05) and showed linear and quadratic trends. Inclusion of vitamin C at 600 mg/kg feed had shown higher lipid and carotenoid contents of female koi carp (p<0.05). Hence, the results revealed that supplementing vitamin C and E in the diet is necessary for the successful reproduction of koi carp.

Koi (Cyprinus rubrofuscus) Seek Out Tactile Interaction with Humans: General Patterns and Individual Differences.

Simple SummaryTo assess the possibility of forming stable and trusting relationships between humans and fishes, we documented the interactions between a familiar human experimenter and seven koi (Cyprinus rubrofuscus). Analyses of video data shows that overall, koi spent more time than expected in close proximity to the human and even sought out physical contact. Moreover, individual fish displayed unique interaction patterns, with some frequently engaging in tactile interaction and others only periodically or rarely doing so. By demonstrating that koi will voluntarily interact with humans and that individual differences play an important role in interaction style, this study provides the first evidence that individuated human–fish relationships may be possible, which has powerful implications for how we think about, treat, protect, and provide care for fish.The study of human–animal interactions has provided insights into the welfare of many species. To date, however, research has largely focused on human relationships with captive mammals, with relatively little exploration of interactions between humans and other vertebrates, despite non-mammals constituting the vast majority of animals currently living under human management. With this study, we aimed to address this gap in knowledge by investigating human–fish interactions at a community garden/aquaponics learning-center that is home to approximately 150 goldfish (Carassius auratus) and seven adult and two juvenile koi (Cyprinus rubrofuscus). After a habituation period (July–September 2019) during which time the fish were regularly provided with the opportunity to engage with the researcher’s submerged hand, but were not forced to interact with the researcher, we collected video data on 10 non-consecutive study days during the month of October. This procedure produced 18~20-min interaction sessions, 10 during T1 (when the experimenter first arrived and the fish had not been fed) and eight during T2 (20–30 min after the fish had been fed to satiation; two sessions of which were lost due equipment malfunction). Interactions between the researcher and the seven adult koi were coded from video based on location (within reach, on the periphery, or out of reach from the researcher) and instances of physical, tactile interaction. Analyses revealed that overall, koi spent more time than expected within reach of the researcher during both T1 (p < 0.02) and T2 (p < 0.03). There were also substantial differences between individuals’ overall propensity for being within-reach and engaging in physical interaction. These results show that koi will voluntarily interact with humans and that individual koi display unique and consistent patterns of interaction. By providing quantitative data to support anecdotal claims that such relationships exist around the world, this research contributes to the ongoing discoveries highlighting the profound dissonance between how humans think about and treat fish and who fish actually are, thereby emphasizing the necessity of stronger moral and legal protections for fishes.

Pharmacokinetics of danofloxacin following intramuscular administration of a single dose in koi (Cyprinus carpio).

To determine the pharmacokinetics of danofloxacin following IM administration of a single dose (10 mg/kg) in koi (Cyprinus carpio). 69 healthy adult koi housed in a 980-L flow-through-system tank. 3 fish were kept as untreated controls, and the remaining 66 fish were assigned to 11 treatment groups with 6 fish/group. Fish in the treatment groups were given a single dose of danofloxacin (10 mg/kg) IM in the left epaxial musculature. Fifteen, 30, and 45 minutes and 1, 4, 12, 24, 72, 96, 120, and 144 hours after administration of danofloxacin, fish in each treatment group were euthanized, and blood samples and samples of liver, spleen, gill, anterior kidney, posterior kidney, skin and muscle, and scales were collected. Plasma and tissue drug concentrations were determined by liquid chromatography-tandem mass spectrometry, and noncompartmental pharmacokinetic analyses were performed. Tissues from the untreated control fish and fish euthanized 144 hours after danofloxacin administration were examined histologically. Maximum plasma concentration (mean, 8,315.7 ng/mL) was reached approximately 45 minutes after danofloxacin administration; plasma elimination half-life was 15 hours. Danofloxacin was detected in all examined tissues from all 6 fish euthanized 15 minutes after drug administration and was detected in some tissues from 3 of the 6 fish euthanized 144 hours after drug administration. For all tissues, results of histologic examination were unremarkable. IM administration of a single dose (10 mg/kg) of danofloxacin in koi resulted in rapid absorption, with maximum plasma concentration reached approximately 45 minutes after drug administration; the drug could still be detected in some tissues 144 hours after administration.

Investigation of a Cyprinid Herpesvirus 1 Disease Episode in a Group of Pond-Reared Koi.

Fifteen adult koi (a variant of Common Carp Cyprinus carpio) simultaneously developed white cutaneous proliferations affecting up to 30% of their bodies. The onset of these lesions (in September 2014) was associated with their return to a remodeled backyard water garden after temporarily being maintained in a plastic swimming pool. A single water temperature taken during the outbreak read 21°C on November 17, 2014. The water garden had no extrinsic heat source, with average ambient temperatures ranging from 9.4 to 26.4°C during the outbreak (September 2014-January 2015). Representative skin biopsies were obtained from two fish; the histologic features included severe epidermal hyperplasia, dysplasia, keratinocyte apoptosis, decreased and haphazardly distributed goblet cells with the absence of club cells, keratinocyte hydropic degeneration, and moderate infiltration by lymphocytes and eosinophilic granular cells. Ultrastructural findings included intranuclear nonenveloped hexagonal nucleocapsids and abundant cytoplasmic-enveloped virions morphologically consistent with the Alloherpesviridae family. Polymerase chain reaction was performed on formalin-fixed, paraffin-embedded shavings from the two biopsied koi targeting the thymidine kinase gene of cyprinid herpesvirus 1 (CyHV-1). Together with the aforementioned findings, these results are consistent with an outbreak of CyHV-1 in a population of adult koi.

Emergence of carp edema virus in cultured ornamental koi carp, Cyprinus carpio koi, in India.

A disease outbreak was reported in adult koi, Cyprinus carpio koi, from a fish farm in Kerala, India, during June 2015. The clinical signs were observed only in recently introduced adult koi, and an existing population of fish did not show any clinical signs or mortality. Microscopic examination of wet mounts from the gills of affected koi revealed minor infestation of Dactylogyrus sp. in a few koi. In bacteriological studies, only opportunistic bacteria were isolated from the gills of affected fish. The histopathological examination of the affected fish revealed necrotic changes in gills and, importantly, virus particles were demonstrated in cytoplasm of gill epithelial cells in transmission electron microscopy. The tissue samples from affected koi were negative for common viruses reported from koi viz. cyprinid herpesvirus 3, spring viraemia of carp virus, koi ranavirus and red sea bream iridovirus in PCR screening. However, gill tissue from affected koi carp was positive for carp edema virus (CEV) in the first step of nested PCR, and sequencing of PCR amplicons confirmed infection with CEV. No cytopathic effect was observed in six fish cell lines following inoculation of filtered tissue homogenate prepared from gills of affected fish. In bioassay, the symptoms could be reproduced by inoculation of naive koi with filtrate from gill tissue homogenate of CEV-positive fish. Subsequently, screening of koi showing clinical signs similar to koi sleepy disease from different locations revealed that CEV infection was widespread. To our knowledge, this is the first report of infection with CEV in koi from India.

The efficacy of alfaxalone for immersion anesthesia in koi carp (Cyprinus carpio)

ObjectiveTo characterize the physiologic and behavioral effects of a single induction dose and two maintenance doses of alfaxalone delivered by water immersion in the anesthesia of koi (Cyprinus carpio). Study designProspective, within-subject complete crossover design. AnimalsSix adult koi (Cyprinus carpio) with a median body weight of 344.5 g (range 292.0–405.0 g). MethodsKoi were immersed in water containing 10 mg L−1 alfaxalone until immobile and then maintained with alfaxalone at either 1 or 2.5 mg L−1 via a recirculating water system. Times for anesthetic induction and recovery periods were recorded. Physiologic and blood gas parameters were evaluated before, during and after the anesthetic trial. Response to noxious stimuli was also assessed. ResultsMedian anesthesia induction time for all fish was 5.4 minutes. Median recovery time was 11.8 and 26.4 minutes in the 1.0 and 2.5 mg L−1 doses, respectively, which were significantly different (p = 0.04). Cessation of opercular movement occurred in 0/6 and 4/6 fish exposed to 1.0 and 2.5 mg L−1 dose respectively. No difference was observed in median heart rate over the duration of the anesthetic events. Response to noxious stimulation was 4/6 and 0/6 in the 1.0 and 2.5 mg L−1 doses respectively. Oxygenation and ventilation did not change during the experiment, but there was a significant decrease in blood pH along with an increase in blood lactate concentration. Conclusion and clinical relevanceAdministration of alfaxalone, via water immersion, as an induction and maintenance anesthesia agent provided rapid and reliable anesthesia of koi with no mortality. The maintenance dose of 2.5 mg L−1 was sufficient to prevent response to noxious stimuli but was associated with a clinically relevant depression in opercular rate.

Emergence of fatal European genotype CyHV-3/KHV in mainland China

Cyprinid herpesvirus 3 (CyHV-3), also known as koi herpesvirus (KHV), is a highly infectious causative agent to common carp and koi worldwide. The virus is mainly consisted of European and Asian genotype isolates. To date, no European genotype CyHV-3 has been found emerging in the East and Southeast Asian regions. In late March 2011, an outbreak of CyHV-3 disease occurred in Guangzhou City, Guangdong Province, China, resulting in the deaths of approximately 200 large-sized adult koi within four weeks. One moribund koi was sampled for CyHV-3 isolation. Thus, a CyHV-3 was isolated in KCF-1 cells and designated as KHV-GZ11. Abundant mature or immature virions in infected KCF-1 cells were observed under a transmission electron micrograph. In addition, intra-nuclear inclusion body-like structures with masses of virions were also observed. Based on the TK and ORF136H genes, the sequence analyses revealed that KHV-GZ11 is a distinct European genotype of CyHV-3. Moreover, the infectivity experiment showed that KHV-GZ11 was highly virulent to koi. In summary, we are the first to confirm the emergence of fatal European genotype CyHV-3/KHV in East and Southeast Asia. Our study will provide new insight to explore the virus origin and epidemiology, as well as its pathogenicity.

Otolith microchemistry of koi carp in the Waikato region, New Zealand: a tool for identifying recruitment locations?

We assessed differences in the otolith microchemistry of koi carp, a colour variant of the invasive common carp Cyprinus carpio, at various locations in the Waikato region of New Zealand. Although koi carp are abundant here, little is known about where and in what habitats they breed. We investigated the feasibility of determining the natal habitats of adult koi carp (in the Waikato River, selected tributaries, and riverine lakes in the catchment) using otolith elemental signatures and employing laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS). Differences in elemental concentrations in water among the sites indicated that variation in otolith microchemistry was likely. Ratios of manganese (Mn), rubidium (Rb), strontium (Sr), and barium (Ba) to calcium (Ca) in otolith edges differed significantly among the sites, and Sr:Ca in the water and otoliths was positively correlated. A discriminant function analysis using Rb, Sr, and Ba accurately classified the otolith edge signatures of koi carp from some locations, but the otolith signatures of koi carp caught from adjacent locations were often indistinguishable. This suggests that our results could have been confounded by either (1) recent movement of koi carp or (2) a lack of differences in water chemistry among sites. Taken together, these results demonstrate that otolith microchemistry can be used to test retrospectively for koi carp migration between sites on a broad scale in theW aikato region, but fine-scale movements may not be detectable

Movements of Radio- and Acoustic-Tagged Adult Koi Carp in the Waikato River, New Zealand

Abstract The movement of koi, a highly colored variant of common carp Cyprinus carpio, was monitored for 18 months in the Waikato River, New Zealand, with both radiotelemetry and acoustic telemetry. Koi had large total linear ranges (mean, 39 km), and most fish (74%) monitored for more than 250 d traveled between the Waikato River and lateral habitat. Differences in total linear range and mean daily movement between years suggest a behavioral response associated with reduced habitat availability during periods of low flow. The movements of koi were highly variable and infrequent, suggesting that important long-range movements are missed in short-term studies (<250 d), resulting in underestimations of total linear range. Our data suggest that large numbers of koi could have been intercepted traveling between lateral habitat and the Waikato River during 1 of 2 years, indicating that point source removal would be highly effective. Received June 12, 2009; accepted January 20, 2011

Movement, social cohesion and site fidelity in adult koi carp, Cyprinus carpio

Abstract Koi carp is an ornamental variant of the common carp, Cyprinus carpio L., that was introduced to New Zealand in the 1960s and has since become a major aquatic pest. A total of 1265 wild adult koi carp were caught by boat electric fishing, dart tagged and released at multiple sites in the lower Waikato River and associated lakes and wetlands between September 2002 and February 2005. Subsequent recaptures by boat electric fishing and recreational fishing returned 76 koi carp (6% of all tagged fish). Of these, 85% were recaptured less than 5 km from their release site; only one fish moved more than 50 km. On seven occasions, pairs or small groups of koi carp (20% of all tag returns) that had previously been tagged and released at the same locations and times were subsequently recaptured together after considerable periods of time at liberty (mean 551 days ± 419 SD). Adult koi carp in the Waikato River showed a high degree of site fidelity, exhibited prolonged social groupings and females moved downstream more often than males.

Acoustic and radio-transmitter retention in common carp (Cyprinus carpio) in New Zealand

Common carp (Cyprinus carpio) are notoriously difficult to monitor in water temperatures above 20°C using telemetry owing to transmitter expulsion. To reduce transmitter loss, radio transmitters were anchored to the pelvic girdle and a polymer coating was applied to acoustic transmitters to reduce tissue irritation in two tank trials. Ten dummy transmitters were surgically implanted in each of four groups of adult koi carp, a highly coloured strain of C. carpio. Water temperatures ranged between 7 and 24°C. After 365 days, the control and test groups of each trial had similar expulsion rates (P ≥ 0.30; two-tailed Fisher’s exact probability test). Expulsion rates for uncoated acoustic transmitters were 60% (n = 6), coated acoustic transmitters 50% (n = 5), unanchored radio transmitters 60% (n = 6) and anchored radio transmitters 90% (n = 9). Expulsions occurred 15–362 days after implantation as a result of ulcers at or near the surgical wound. Bacterial infection of the wound appears to be the primary mechanism for transmitter expulsion.

Plasma biochemical reference intervals for koi

To assess reproducibility of an in-house tabletop biochemical analyzer for measurement of plasma biochemical analytes and establish reference intervals in adult koi. Prospective study. 71 healthy adult koi. Plasma was analyzed for concentrations or activities of albumin, alkaline phosphatase, alanine aminotransferase, aspartate aminotransferase, bile acids, BUN, calcium, cholesterol, creatine kinase, gamma-glutamyltransferase, globulin, glucose, K, Na, P, total bilirubin, total protein, and uric acid. Duplicate samples were evaluated by use of the intraclass correlation coefficient to determine reproducibility. To assess the magnitude of differences between replicate samples, the absolute mean difference, SD, and minimum and maximum values were calculated for each analyte. Median values and reference intervals were calculated. Intraclass correlation coefficient values were excellent for all analytes except alanine aminotransferase (good), Na (poor), gamma-glutamyltransferase (poor), and P (poor). Reference intervals were established. The in-house tabletop biochemical analyzer had good precision for measuring most plasma biochemical analytes. Further research and comparison with other reference procedures are needed before reference intervals and precision can be established for globulin, Na, P, K, and albumin. Aquatic veterinarians may be able to use the reference intervals for adult koi as an important diagnostic tool or as part of a fish wellness program, as commonly done in other domestic species.

A Herpesvirus Associated with Mass Mortality of Juvenile and Adult Koi, a Strain of Common Carp.

A herpesvirus was isolated from adult koi, a strain of common carp Cyprinus carpio, suffering mass mortality in two outbreaks-one in the mid-Atlantic region of the United States and the second in Israel. The principal external signs of dying fish were pale and irregularly colored gills. There were few consistent internal signs in either outbreak. The most prominent microscopic lesions were in the gills, where hyperplasia and necrosis of the epithelium were severe. Other lesions included interstitial nephritis, splenitis, and enteritis. Affected cells often contained nuclei with marginated chromatin and faint intranuclear inclusions. Typical herpesvirus particles were present in branchial epithelial cells, hepatocytes, and among circulating leukocytes. Inoculations of the koi fin (KF-1) cell line with tissue extracts from the gill and kidney-spleen resulted in cytopathic effects characterized by severe vacuolation first detected after 7 d incubation at 20°C. Exposures of adult koi to the herpesvirus as propagated in KF-1 cells by bath or intraperitoneal injections resulted in 80-100% mortality during a 26-d period, and the virus was reisolated from the gill, kidney, liver, spleen, intestine, and brain of dead fish. The viral agents from koi in Israel and the United States appear to be similar if not identical; both could be distinguished from Herpesvirus cyprini by indirect fluorescent antibody tests with rabbit anti-H. cyprini serum. Other factors should be examined but we strongly suspect that this newly recognized koi herpesvirus (KHV) has the potential to be a significant cause of mortality among koi and presumably common carp.