The effect of short-time Artemia spp. feeding on growth performance and cumulative survival rate of barbel (Barbus barbus) larvae were studied under controlled aquaria conditions during the 21-day larval period. Three different diets (presenting reduced Artemia feeding) were tested for first exogenous nutrition of larvae (since 13 days post hatch):(1) artificial feed (Asta); (2) Artemia nauplii for 7 days followed by artificial feed; (3) Artemia nauplii for 14 days followed by artificial feed. The longer period of live food statistically improved growth of larvae (W = 174 ± 20 mg and SGR = 14.5 ± 0.5% d −1 ). The artificial dry food Asta without the addition of Artemia nauplii caused statistically decreased growth (W = 135 ± 22 mg and SGR = 13.1 ± 0.7% d −1 ). However, the growth of larvae with the short period of Artemia nauplii (W = 153 ± 25 mg and SGR = 13.8 ± 0.7% d −1 ) did not differ compared to either group. All used feeding diets did not have a significant effect on the cumulative survival rate of larvae ranging from 73 ± 1% to 74 ± 1% at the end of the larval rearing period. The effects of the rearing environment on growth performance and survival rate of juveniles were tested under intensive controlled conditions in aquaria and troughs for 84 days following the larval period (from 34 to 118 dph). The environment of the troughs caused significantly decreased growth (W = 2079 ± 433 mg and SGR = 3.1 ± 0.05% d −1 ) of juveniles compared to ones reared in aquaria (W = 3236 ± 264 mg and SGR = 3.6 ± 0.1% d −1 ) at the end of the juvenile rearing period. Nevertheless, rearing environment did not have a significant influence on the cumulative survival rate of barbels (S C = 90 ± 4% and 81 ± 3% in aquaria and troughs, respectively).

Juvenile noble crayfish, Astacus astacus and spiny-cheek crayfish, Orconectes limosus were reared from the 2nd and the 3rd developmental stage (i.e. since the stage of independence), respectively, until the end of the growing season. The first period revealed very low survival rate of O. limosus in the communal stock (7 ± 6.2%), probably caused by predation of A. astacus. Separately reared O. limosus proved significantly higher survival rate (49 ± 9.2%) than those in the communal stock with A. astacus. The latter species also showed the highest survival rate in this case (90 ± 7.1%). This was not found to differ from the survival rate of separately reared noble crayfish (86 ± 3.1%). In general, both the significant effect of bigger size of A. astacus than that of O. limosus and higher intra-specific cannibalism of O. limosus were reflected during the first phase of rearing. Size and weight of both species were equivalent 11 weeks after hatching (8 weeks of rearing). The higher cumulative survival rate was reached in the intraspecific culture of A. astacus (90%) while low cumulative survival of both species was found in communal stock (less than 50%) in the second phase of rearing. At the end of the growing season, 19-week-old O. limosus attained a higher mean size and weight but were more variable in the group (29.3 ± 5.17 mm and 616.4 ± 412.53 mg) than A. astacus (21.2 ± 1.82 mm and 229.9 ± 59.45 mg). Single and communal stock did not differ. Growth of O. limosus was much faster than that of A. astacus.

ABSTRACT:The effect of three different anaesthetics, 2-phenoxyethanol (0.6 ml/l), Propiscin (0.75 ml/l) and clove oil (0.033 ml/l), on adult tench (Tinca tinca L.) of mean body weight 260 g (66-583 g), of both sexes was tested at four different water temperatures (17.9; 20.4; 22.6 and 25.1°C). The time periods necessary for the induction of particular characteristic phases of anaesthetisation and recovery were evaluated. At all temperatures, the statistically longest induction of anaesthesia (P < 0.05) and longest recovery (P < 0.01) were registered with Propiscin. With clove oil and 2-phenoxyethanol, the time period necessary for induction of phase II b anaesthesia statistically declined (P < 0.05) with rising temperature, however, this phenomenon was not seen with Propiscin.

ABSTRACT:The aim of the study was to compare physiological statuses of stripped and not stripped tench females with ovulation induced by GnRHa or carp pituitary extract (CPE). The comparison was based on selected biochemical stress indices (cortisol, glucose), condition (TP, TGA), and cell membrane characteristics (ALT, AST, CK). In the first and in the second year, 37 and 29 tench females were monitored, respectively. No differences in the values of biochemical parameters in either period were found between the two groups of stripped female tench whose ovulation was induced by GnRHa and CPE, respectively. No significant differences in TP, TGA, ALT, AST and CK values were found between the groups of stripped and not stripped females with ovulation induced by GnRHa or CPE. Different values were found in stress indices, specifically in glucose concentrations. A significant increase (P < 0.01) in glucose concentrations was found in tench females immediately after stripping and, in not stripped females, about 48 hrs after ovulation induction. Both artificial stripping and the inability to release eggs are important stress factors for female tench.

The ide Leuciscus idus (Linnaeus 1758) belongs to autochthonous, less frequent and vulnerable fish species in the frame of ichthyofauna of the Czech Republic. It was the reason for testing the possibility of captive breeding and production of fry in a controlled environment. The goal of this paper was to find the optimal transfer time of ide larvae from live food (Artemia salina nauplii) to dry starter feed providing good survival and growth. At the end of the experiment, high values of cumulative survival (in percentages) and individual weight (in milligrammes) were found for ide fry in groups D (90.6%, 178.6 mg; 15 days A. salina + 10 days starter feed), A (89.9%, 169.9 mg; A. salina only) and C (88.6%, 160.4 mg; 10 days A. salina + 15 days starter feed). Significantly lower values of the given parameters were found in group B (57.1%, 92.6 mg; 5 days A. salina + 20 days starter feed), and the lowest ones were in group E (29.8%, 75.6 mg; starter feed only). Mean values of the level of ontogenesis at the end of the experiment in fry of A-E groups were analogous to length and weight growth. Groups D, C and A consisted of juveniles only (J1, J2), and groups B and E consisted of larvae and juveniles (L4, L5, L6, J1, J2). Condition and production parameters [Fulton's coefficient of condition (FWC), total length (TL), weight (w), specific growth rate (SGR), food conversion ratio (FCR), cumulative survival] and relationships between basic lengths TL, fork length (FL) and standard length (SL) were evaluated.