Amino Acid Composition in Fillets of Mirror Crossbreds Common Carp (Cyprinus carpio, Linnaeus 1758)

The aim of the study was to determine the amino acid composition in fillet proteins of newly bred mirror carp lines. In the experiments, the Hungarian mirror carp (M2) were used at the maternal position. These were crossed with male carp of other breeds (top crossing). They included the Hungarian mirror carp (M2) for the production of a pure line, the Hungarian mirror line (L15), the Israeli breed (DOR70) and the Northern mirror carp (M72). The scaly hybrid of the Ropsha (ROP) and the Tataj (TAT) carp was used as a control. In view of the genetic specification of the carp groups monitored, numerous differences (P P sum, NEAAsum) were found between the scaly control (ROP × TAT) and the pure line M2. Higher amino acid values were found in control hybrids. Compositions of amino acids in fillet muscle tissue of experimental mirror carp (M2 × L15, M2 × DOR70) were practically identical. Compared to the controls (ROP × TAT), these carp groups contained less (P P < 0.01). In terms of sex differences, the greatest amounts of amino acids were found in fillets of male ROP × TAT controls, the amino acid compositions in male and female mirror carp were practically the same. In this type of evaluation, i.e. regarding amino acid composition, the only carp comparable with the ROP × TAT control is the M2 × M72 hybrid

Efficacy Testing of Orally Administered Praziquantel to Common Carp Naturally Infected by Caryophyllidean Tapeworms (Platyhelminthes: Eucestoda)

The aim of the study was to assess the effects of orally applied praziquantel on the treatment efficacy against most abundant tapeworms (Atractolytocestus huronensis Anthony, 1958 and Khawia sinensis Hsü, 1935) of common carp (Cyprinus carpio Linnaeus). Naturally infected fish (1.5-year-old; K1-2) were divided into 6 groups. Three trial groups were administered praziquantel mixed in heat-treated amyloid vehicle (at doses of 50 mg kg-1 body weight). In 3 groups of control, the fish were administered amyloid vehicle only. Fish were examined using gut dissection 2, 4 and 6 days after the administration. The location, intensity and prevalence of individual species of tapeworms were recorded. A. huronensis and K. sinensis were found in the gut of carp together. A. huronensis was situated in the oesophageal part of foregut, and K. sinensis came after – immediately before the first intestine loop, of the intestines of carp. The invasion of A. huronensis was fully eliminated in all trial groups after 4 days whereas some specimens of K. sinensis still persisted in the gut of few fish. The full elimination of both parasites was observed 6 days after administration. Our results showed that elimination of K. sinensis takes longer than elimination of A. huronensis. The dose of 50 mg kg-1 of orally administered praziquantel is effectual to control A. huronensis and K. sinensis infections in common carp successfully, however, a significant decrease of the number of parasites was also caused by a single oral administration of big bolus vehicle and leaving unfed fish in the clean water

Influence of geographic origin on post-stocking survival and condition of European grayling (Thymallus thymallus) in a small river

The post-release survival and condition of 1+ year old European grayling Thymallus thymallus reared in a local (Husinec) and two 250–300 km distant, hatcheries (Pardubice and Hynčice) were evaluated by the recapture of tagged fish five months after release into the Blanice River, Czech Republic, the fish population of which was depleted by cormorant predation during several previous winters. The fish were marked using Visible Implant Elastomer tags and released into six sites along the river in May 2014: 100 locally sourced fish and 100 of a strain from a distant source per site. Significantly higher recapture of Husinec (33%) than Pardubice (20%) was found at one site but was offset by results in the remaining two sites into which they were stocked. Significantly higher site fidelity was shown by Husinec (12%) than Hynčice (7%) fish in the three sites. Lower initial weight and condition factor of the Husinec fish was equal to or higher than fish from the distant hatcheries at recapture. Some differences in final weight, length, and condition factor were found among groups regardless of release site. Lower recapture rate, growth, and condition were displayed in fish released into the three downstream sites (Husinec 1 and Hynčice). The results indicated the potential for successful use of non-autochthonous stock for grayling population recovery

Stressful Daylight: Differences in Diel Rhythmicity Between Albino and Pigmented Fish

In laboratory experiments, variously colored strains of animals, including those with albino phenotypes, are commonly used. The melanocortin theory suggests, however, that coloration phenotypes alter animal physiology and behavior. Animals with the albino phenotype show photoreceptor degradation associated with lowered visual accuracy, escape reactions, etc., presumably accompanied by prevailing nocturnal activity and lowered aggressiveness. This assumption was tested in small groups of albino and pigmented European catfish, Silurus glanis, during the diel cycle. The frequency of agonistic interactions was observed during mutual contests for shelters, and subsequently, blood plasma, brain, gill, and liver samples were collected to evaluate stress parameters. In an experimental arena with shelters, the light/dark rhythmicity of locomotor activity and aggressiveness of the two phenotypes were comparable; the peak was observed at night, and a lower peak was observed at dawn. In an experimental stream without shelters, the peak of locomotor activity occurred at night for only the pigmented phenotype. In the evaluation of 4 antioxidants and 1 oxidative stress indicator, representing a total of 15 indices, albino fish showed significant rhythmicity for 8 indices, whereas pigmented catfish showed significant rhythmicity for 5 indices. The production of blood stress parameters with the peak during the day occurred only in albino fish. A complex model was fitted with the aim of evaluating the links between behavioral and biochemical indices. Time periodicity was modeled using a sine wave and confirmed parallel courses of agonistic interactions in the catfish groups; the peak at dawn was associated with a 4.08-fold (conf. int. 3.53–4.7) increase in such interactions. The changes in glucose and superoxide dismutase concentrations varied with phenotype, while the effects of cortisol, lactate and catalase did not. In summary, the rhythmicity of locomotor activity and changes in the aggressiveness of catfish were influenced by shelter availability, and the effect of light-induced stress was more apparent in albino fish than in pigmented conspecific fish. The results suggested that laboratory-raised animals with pigmentation patterns naturally occurring in the wild show more reasonable values during experiments than those with an albino phenotype