In a laboratory experiment at 28°C, four commercial starters (Carp Starter, Uni Starter, Perla Plus, Asta) were fed intensively to 11-month-old juvenile tench Tinca tinca of initially 41 mm TL and 0.70 g BW, over a period of 120 days. Frozen chironomid larvae were fed to fish below satiation as a reference diet for comparison of the fish body chemical composition. Final survival rates of 99-100% and satisfactory growth were attained with all dry diets, ranging from 73.3 (Carp Starter) to 84.8 mm TL (Asta) and from 5.39 (Carp Starter) to 8.09 g BW (Perla Plus). External body deformities of up to 96.4% specimens appeared in those fed Uni Starter, Carp Starter and Perla Plus, whereas 0% were recorded for Asta and chironomids. Fish in groups with deformities showed significantly elevated lipid content in their bodies, lower ash content and higher condition coefficient values. Juveniles in groups without deformities did not substantially change lipid content, but the ash content increased. Thus, among four dry diets studied, only Asta starter can be fed effectively and safely to juvenile tench reared intensively under controlled conditions.

Duplicate groups of tench (Tinca tinca) juveniles (mean weight 0.69 g) were fed at 28°C for 70 days either a commercial formulated diet, Futura, or frozen Chironomidae larvae at four levels: below satiation, at about satiation, above satiation and well above satiation. These are represented by the feeding groups F1-F4 and C1-C4, respectively. No mortality was observed throughout the experiment. In groups F2-F4 a considerable incidence of uneaten food (>40% observations), deformities of the caudal penduncle, retarded growth, elevated condition coefficient (>1.2), reduced amounts of minerals in the tissue (<10% dry matter), high C/N ratio (>5) and high caloric value of the tissue (>28 J mg )1 dry matter) (the latter two suggesting excessive fat deposits), were found. The combination of these indices was indicative of overfeeding in fish fed the Futura diet at the daily doses ‡2.7% fish biomass. First symptoms of overfeeding: a considerable incidence of uneaten food, retarded growth, and elevated C/N ratio were observed in the group fed Chironomidae larvae at the highest level, (C4, wet Chironomidae 20.7% of the fish biomass daily, that is, 3.9% of dry chironomids per fish biomass and day). Thus, restricted daily doses of formulated diet not exceeding 2.5% fish biomass are recommended for tench juveniles aged 130-200 days post hatch. Safe daily doses of frozen Chironomidae (in terms of larvae dry weight) remain below 3.5% of fish biomass.

The present 20-day trial was performed in order to improve growth of tench Tinca tinca (L.) larvae reared intensively in a controlled environment. Larvae of 4.53 mm initial length, 45 per dm 3 , were fed each day with live Artemia nauplii for 12, 18 or 24 h at 28°C. Final survival rates were very high in all treatment groups, ranging from 88.9 to 91.8%. Duration of daily feeding significantly affected growth and final condition, expressed by Fulton's coefficient (K) (P £ 0.05, Duncan's test). The fastest larval growth (17.6 mm total length, TL; 88.8 mg body weight, BW) and the best condition (K ¼ 1.54) were recorded in the group fed 24 h each day. The second best results were attained with the larvae fed 18 h a day (16.5 mm TL, 67.9 mg BW, K ¼ 1.40) whereas those fed 12 h daily grew the slowest (13.5 mm TL, 31.7 mg BW) and showed the worst condition (K ¼ 1.19). Thus, to maximize growth and condition of tench larvae being reared at the optimal growth temperature, intensive 24 h feeding is necessary.

22Highlights 24 1. Differences in mortality rates during SVCV and CyHV-3 infections were recorded in carp 25 strains. 26 2. The higher resistance of the Rop strain was related to lower virus load and replication. 27 3. The magnitude of type I IFN response was not positively correlated with survival. 28 4. CyHV-3 has an ability to limit IFN response induced by sensing viral DNA by cells. 29 30 Abstract 34 Carp from breeding strains with different genetic background present diverse levels of 35 resistance to viral pathogens. Carp strains of Asian origin, currently being treated as Cyprinus 36 rubrofuscus L., especially Amur wild carp (AS), were proven to be more resistant to koi 37 herpesvirus disease (KHVD; caused by cyprinid herpesvirus 3, CyHV-3) than strains originating 38 from Europe and belonging to Cyprinus carpio L., like the Prerov scale carp (PS) or koi carp 39 from a breed in the Czech Republic. We hypothesised that it can be associated with a higher 40 magnitude of type I interferon (IFN) response as a first line of innate defence mechanisms against 41 viral infections. To evaluate this hypothesis, four strains of common carp (AS, Rop, PS and koi) 42were challenged using two viral infection models: Rhabdovirus SVCV (spring viremia of carp 43 virus) and alloherpesvirus CyHV-3. Infection experiments confirmed significant differences in 44 mortality between the analysed carp strains. The infection with SVCV induced a low mortality 45 rate and the most resistant was the Rop strain (no mortalities), whereas the PS strain was the most 46 susceptible (survival rate of 78%). During CyHV-3 infection, Rop and AS strains performed 47 better (survival rates of 78% and 53%, respectively) than PS and koi strains (survival rates of 48 35% and 10%, respectively). The evaluation of virus loads and virus replication showed 49 significant differences between the carp strains, which correlated with the mortality rate. The 50 evaluation of type I IFN responses showed that there were fundamental differences between the 51 virus infection models. While responses to the SVCV were high, the CyHV-3 generally induced 52 low responses. Furthermore, the results demonstrated that the magnitude of type I IFN responses 53 did not correlate with a higher resistance in infected carp. In the case of a CyHV-3 infection, 54 reduced type I IFN responses could be related to the potential ability of the virus to interfere with 55 cellular sensing of foreign nucleic acids. Taken together, the results broaden our understanding of 56 how common carp from different genetic lines interact with various viral pathogens. 57 monitoring the development of the infection in four tissues and subsequently measuring type I 113 IFN responses. Further in vitro studies were performed to better characterise anti-IFN actions of 114 CyHV-3. 115 116 117 For the infection experiments, the carp were transported to the National Veterinary 131Research Institute in Pulawy, Poland at a mean weight of 10.3 ± 8.2 g and placed at 18 °C in a 132 flow through system two week...

The growth and survival of rudd <I>Scardinius erythrophthalmus</I> (L.) were evaluated in a laboratory at 25°C. In 20-day Experiment 1, first-feeding larvae at the age of 4 days post-hatch (initially: TL = 5.7 mm, BW = 0.9 mg) were fed live <I>Artemia</I> nauplii or commercial dry feed (Aller Futura Larvae, AFL) or combinations of both. Even the longest period of initial feeding of nauplii (6 days) was insufficient to obtain satisfactory larval growth after weaning to AFL (TL = 12.4 mm and BW = 17.7 mg vs. TL = 18.9 mm and BW = 68.5 mg for the nauplii-fed fish, significant differences). Nauplii-fed older larvae (24 days post-hatch) were then used in Experiment 2, in which they were fed AFL or Ewos AgloNorse (EAN) dry feeds for 40 days. The EAN diet proved to be significantly (<I>P</I> ≤ 0.05) superior to AFL regarding the final fish growth (TL = 36.5 mm and BW = 506.8 mg vs. TL = 33.4 mm and BW = 392.0 mg ), final survival rates (97.6% vs. 100%) and the incidence of spinal deformities (0% vs. 13.5%).