Isometric twitch tension of lateral muscle in carp, Cyprinus carpio L., with sekoke disease

Abstract. Changes in blood properties and the chemical components, histology and isometric twitch tension of lateral muscle were studied in carp, Cyprinus carpio L., showing clinical signs of sekoke disease induced by a diet containing oxidized oil. When compared to normal fish, sekoke fish were found to have significantly lower mean blood pH, haematocrit, haemoglobin concentration and muscle water content. However, plasma lactate, lipoperoxide and total lipid concentrations were significantly higher in sekoke fish. It was found that in sekoke fish the maximum tension and the number of isometric twitches leading to complete fatigue of lateral muscle were greatly reduced. Histological studies confirmed that these reductions were related to the degree of structural damage within this tissue.     

Cell-mediated protection in carp, Cyprinus carpio L., against Aeromonas hydrophila

Abstract. The mechanism of protection against Aeromonas hydrophila infection in carp was studied. Recipient fish, into which pronephric cells from carp previously immunized by dipping in bacterial crude lipopolysaccharide (LPS) at 25°C for 2h were transferred, demonstrated almost the same level of protective ability as an immunized control group. The protective ability was transmitted by non-adherent (to nylon fibre) immune pronephric cells. These non-adherent cells were damaged by anti-carp thymocyte serum and were, thus, considered to be T-like cells. The protective ability was depressed in immunized carp treated with anti-carp thymocyte serum in vivo and was also remarkably reduced in immunized carp whose macrophage function was impaired by Dextran sulphate-500 treatment. These results indicate that the protection shown by carp immunized by dipping in crude LPS is dependent on cellular immunity regulated by a T-like cell-macrophage system.     

Responses of fingerling carp, Cyprinus carpio L., to dietary lysine

Abstract. The lysine requirements of fingerling carp, Cyprinus carpio L., for optimum growth and efficiency of food utilization were determined in two experiments by the addition of graded supplements of lysine to a basal diet deficient in this amino acid.
The lysine requirement was estimated to be around 14.5 g/kg dry matter at an ambient temperature of 20°C. At 25°C continuing growth responses occurred up to a dietary lysine concentration of 22.4 g/kg DM. However, when these responses are considered in relation to daily lysine intake, the gross efficiency of utilization of dietary lysine for growth appeared to be unaffected by environmental temperature.
Dietary lysine concentrations exerted no consistent effect upon carcass composition of carp. However, fat deposition tended to increase as food intakes increased in response to lysine additions or to elevated ambient temperature.     

Regression effect of carp, Cyprinus carpio L., peripheral blood lymphocytes on CHV-induced carp papilloma

Abstract. The effect of peripheral blood lymphocytes (PBL) of carp, Cyprinus carpio L., was investigated on the regression of papilloma which had been induced in carp experimentally infected with Herpesvirus cyprini (CHV). The regression of the papilloma was delayed in carp injected with anti-carp PBL serum. In addition, the spontaneous cytotoxic activity of PBL derived from normal carp was suppressed by injection with anti-carp PBL serum. These results suggest that the spontaneous cytotoxic activity of carp PBL plays an important role in the regression of carp papilloma.     

Immune protection in carp, Cyprinus carpio L., after immunization with Aeromonas hydrophila crude lipopolysaccharide

Abstract. Vaccination with crude lipopolysaccharide (LPS) induced better protection against infection with Aeromonas hydrophila in carp than vaccination with formalin killed vaccine. Dipping fish in vaccine for 2 h at 25°C was more effective than intraperitoneal injection of the vaccine in procedural simplicity, lower stress loading and the degree of protection acquired. In carp immunized with crude LPS by the dip method, antibodies were not detected by bacteriai agglutination, passive haemagglutination and the agar diffusion tests. The results indicate that the protection against A. hydrophila infection in carp is not dependent on humoral immunity.     

Koi herpesvirus epizootic in cultured carp and koi, Cyprinus carpio L., in Taiwan

Koi herpesvirus (KHV) poses a significant threat to cultured koi and common carp, both Cyprinus carpio L. Since the first reported case in Israel in 1998, KHV has rapidly spread worldwide. This study investigates the spread of KHV to Taiwan by collecting 49 cases of suspected common carp and koi infections from 2003 to 2005 for analysis. Clinical signs included lethargy, anorexia, increased respiratory movements and uncoordinated swimming. Hyperaemia, haemorrhage on body surface and necrotic gill filaments were recorded. Gill epithelial hyperplasia, necrosis and eosinophilic intranuclear inclusion bodies were observed by histological examination, while virions were detected using transmission electron microscopy. By detecting the presence of the KHV thymidine kinase (TK) gene and the KHV 9/5 gene using polymerase chain reaction (PCR), 37 cases were identified as KHV-positive, and the cumulative mortality of infected fish was 70-100%. Positive cases showed identical sequences for the genes analysed, implying that they were of the same origin. For the KHV 9/5 gene sequence, these cases exhibited 100% identity with the Japanese strain (TUMST1, accession number AP008984) and 99% identity with the Israeli (KHV-I, DQ177346) and US (KHV-U, DQ657948) strains. Additionally, a loop-mediated isothermal amplification (LAMP) assay was performed and found to be more sensitive than PCR tests, suggesting its potential use as a rapid diagnostic method for KHV. This is the first epidemiological study of KHV infection in cultured common carp and koi in Taiwan.     

Blood oxygen tension and content in carp, Cyprinus carpio L., during hypoxia and methaemoglobinaemia

Carp respond to water hypoxia with an evaluation in the rate of gill ventilation. In order to characterize closer the adequate stimulus for the increase in respiratory drive specimens of carp, Cyprinus carpio L., were exposed simultaneously to moderate environmental hypoxia (P^wO²? 75mmHg, 10kPa) and elevated water nitrite concentration (089 ± 0-lmmol/l) for 24h. The differential effects of these treatments were utilized to distinguish between the responses to an immediate reduction in water and arterial Po_a (P,O²), and to the slowly developing reduction of arterial oxygen content (C^aO²) and functional oxygen saturation (S^aO²). After onset of hypoxia gill ventilation quickly increased, leading to a reduction in P_aCO₂. Slowly rising blood methaemoglobin levels resulted in a gradual decline in C^aO² and S^aO² over 24h, whereas P002 remained steady for the entire exposure period. This pattern of lowered P^aco² and P_aO₂, essentially constant for 24 h, together with the lack of any correlation with changes in C^aO², suggests PO₂ (P^a,O² and/or P^wo²) as the primary stimulus in the regulation of ventilation of carp.     

Detection of koi herpesvirus in common carp, Cyprinus carpio L., by loop-mediated isothermal amplification

Loop-mediated isothermal amplification (LAMP) is a novel method that amplifies DNA with high specificity and rapidity under isothermal conditions. In this study, using the LAMP method, a protocol for koi herpes virus (KHV) detection in common carp was designed. A set of four primers, two inner and two outer, were designed based on the sequence of the thymidine kinase (tk) gene of KHV. Time and temperature conditions for detection of KHV were optimized for 60 min at 65 degrees C. The detection limit using LAMP was found to be similar to that by polymerase chain reaction. In this study, we have developed a highly sensitive and rapid diagnostic procedure for detection of KHV infection in common carp.     

Enhancement of Hsp70 synthesis protects common carp, Cyprinus carpio L., against lethal ammonia toxicity

Exposure to TEX‐OE^®, a patented extract of the prickly pear cactus (Opuntia ficus indica) containing chaperone‐stimulating factor, was shown to protect common carp, Cyprinus carpio L., fingerlings against acute ammonia stress. Survival was enhanced twofold from 50% to 95% after exposure to 5.92 mg L^?1 NH₃, a level determined in the ammonia challenge bioassay as the 1‐h LD50 concentration for this species. Survival of TEX‐OE^®‐pre‐exposed fish was enhanced by 20% over non‐exposed controls during lethal ammonia challenge (14.21 mg L^?1 NH₃). Increase in the levels of gill and muscle Hsp70 was evident in TEX‐OE^®‐pre‐exposed fish but not in the unexposed controls, indicating that application of TEX‐OE^® accelerated carp endogenous Hsp70 synthesis during ammonia perturbation. Protection against ammonia was correlated with Hsp70 accretion.     

Antibody response of two populations of common carp, Cyprinus carpio L., exposed to koi herpesvirus

Common carp, Cyprinus carpio L., exposed to koi herpesvirus (KHV) may become persistently infected and populations containing such virus-infected individuals may transmit the virus to other fish when co-habited. Detection of virus-infected fish in a population is thus critical to surveillance and control programmes for KHV. A study was therefore designed to detect anti-KHV serum antibodies, with an enzyme-linked immunosorbent assay, in common carp following experimental exposures to KHV under varying environmental conditions. The study determined that a proportion of fish within a population experimentally exposed to KHV (at least 10–25%) develop high antibody titres (1/1600 or greater) to the virus, and this immunological response was detectable for several months (observed at the termination of the experiments at 65, 46 and 27 weeks post-exposure). Furthermore, this response was detected in one population of fish that did not succumb to a high level of mortality when maintained at water temperatures that were non-permissive for KHV. Elevating the water temperatures to permissive conditions for KHV resulted in recurrence of disease despite the presence of anti-virus antibodies, suggesting that serum antibodies alone are not protective under the conditions of our trials.     

Optimum food particle size in relation to body size of common carp, Cyprinus carpio L., fry

Abstract. An investigation was conducted under laboratory conditions to determine the optimum food particle size of an inert diet for common carp fry ranging in size from 15 to 466mg body weight and 13 to 31 mm total length (TL). Speed of consumption of a standard quantity of food was used as a measurement of feeding preference/efficiency for different particle size ranges. It was observed that for carp of this size range preferred food particle size increases with fish size. On the basis of ingestion time and feeding behaviour, food particle sizes in the ranges 125-300μm. 300-500μm, 300-790μm and 500-1000μm diameter were found to be most appropriate for carp fry weighing 15-23mg(TL 13-18), 46-97 mg(TL 17-22), 105-209 mg (TL 20-25) and 210-466mg (TL 24-31) respectively. This study also demonstrated that for carp fry of these size ranges the mean preferred food particle sizes are about 02-04 that of mouth size. Based on this relationship, general recommendations are made on the optimum food particle sizes for different size classes of carp fry reared under hatchery and nursery conditions.     

Pharmacokinetics and tissue distribution of oxytetracycline in carp, Cyprinus carpio L., following different routes of administration

Abstract. The objective of this pharmacokinetic study was to investigate absorption, distribution, elimination and bioavailability of oxytetracycline (OTC) in carp, Cyprinus carpio L ., after different routes of administration, OTC was administered intravenously (i.v.), intramuscularly (i.m.) and orally at 60 mg/kg body weight. OTC levels were determined in plasma and several tissues. Analysis of the plasma drug concentration-time curves following i.v. OTC injection revealed three distinct phases. A three-compartment open model was used to derive pharmacokinetic parameters. Compared to mammals, a very extended final elimination half-life was observed (139.8±38.1 h). Following i.m. OTC administration, C_max was 56.8±10.9μg OTC/ml at 14 h post-injection. The Vd area was 2.1 ± 0.66 1/kg. Extreme differences were observed with respect to bioavailability following i.m. and oral administration; approximately 80 and 0.6%, respectively. Following i.m. injection tissue OTC determinations revealed that the drug was accumulating in pronephros, bone tissue and scales. After 21 days the OTC concentrations were 2.9±0.8, 5.2±0.3 and 4.7±3.1 μg/ ml, respectively. In tissue samples from the dorsal region (muscle), including the injection site, OTC could not be demonstrated at that time. The pharmacokinetic data are discussed in relation to the susceptibility of the immune system of fish for modulation.     

The histopathology of carp, Cyprinus carpio L., exposed to microcystins by gavage, immersion and intraperitoneal administration

Carp liver, gills, intestine, kidneys, heart and spleen were studied by histology after the fish were exposed to microcystins by gavage, immersion and intraperitoneal administration. Intraperitoneal inoculation with microcystins caused necrosis or dose- dependent degeneration in the liver, gills and kidneys. Gavaging with microcystins caused changes in the histopathology of the liver and gills. Cellular degeneration and necrosis occurred in the liver, gills and kidneys when carp were introduced to a tank containing 1.7 μg ml^?1 of microcystins. Lesions were not observed in the heart, spleen or intestines from any of the treated carp. Microcystins administered by intraperitoneal injection at a concentration of 50 μg kg^?1 were lethal to all fish within 8 h, while gavaging with 250 μg kg^?1 of microcystins caused minimal damage in the tissues studied.     

Changes in skin mucus of common carp,Cyprinus carpio L., after exposure to water with a high bacterial load

Water in aquaculture systems may contain a high load of microorganisms. Reduction in overall bacterial tank water load improves fish health and growth parameters. In this study, the effect of an increase of overall bacterial load in tank water on carp skin mucus was assessed. Intracellular and released high molecular weight glycoproteins (HMGs) of carp skin mucus were analysed for changes using histological, histochemical and biochemical techniques. Increase of bacterial load did not induce obvious clinical responses in carp, but the skin of exposed carp responded quickly. The amount of skin mucus HMGs isolated increased as well as their total glycosylation. An increased goblet cell number was observed for all carbohydrate stainings, but most clearly for acidic glycoconjugates. A change in the terminal presence of some sugars was also seen. After the initial response of carp, an adaptation to the higher bacterial load in the water appeared to occur as mucins had a higher glycosylation. The changes observed suggest that these skin mucus adaptations are part of a primary defence mechanism of mucosal epithelia, even at a low pathogenic pressure.     

Upper lethal and rearing temperatures for juvenile common carp, Cyprinus carpio L., and silver carp, Hypophthalmichthys molitrix (Valenciennes)

Abstract. The ultimate upper lethal temperature (UULT) was 43.0 or 46.0°C for common carp and 43.5 or 46.5°C for silver carp, depending on the method of calculation. The influence of fish age on lethal temperature values was low. Using the relationship between the UULT and the optimum growth temperature the latter was calculated as being 38°C for common carp and 39°C for silver carp. No significant differences were found in survival of fish reared at lower and higher temperatures when proper food was used.     

Apparent digestibility coefficient of protein sources for carp, Cyprinus carpio L.

The digestibility of various diet components as protein sources for common carp, Cyprinus carpio L., at 500–800 g was studied by using an inert marker in the feed and collecting the faeces by stripping. Protein in fish meal (83.8%) and soybean meal (69.8%) were significantly more digestible than that of poultry meal (47.2%). Energy digestibility tests gave the following results: fish meal 93.4%, soybean meal 74.7% and poultry meal 63.9%. It was evident that the ability of carp to digest proteins is very high, and that they can utilize proteins as the main component of their diet.