Considering Two Aspects of Fish Welfare on African Catfish (Clarias gariepinus) Fillet throughout Postmortem Condition: Efficiency and Mechanisms.

Knowledge about fish welfare and its impact on fish fillet quality is still insufficient. Therefore, the influence of two aspects of fish welfare (slaughtering method: bled and unbled fish; fish stock densities: 90, 120, and 150 kg·m-3) on African catfish fillet quality during postmortem conditions was investigated. The aim of study was to determine (i) the efficiency of bleeding on oxidation progress and (ii) the influence of stock density on fillet quality. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) showed a higher protein loss in the unbled than in the bled groups, especially in the heavy myosin chain (MHC) band. However, density did not show any influence on protein profile. Western blot analysis showed fewer oxidized carbonyls in the bled than in the unbled groups; higher oxidation development, microbial growth, and lower hardness were observed in unbled fillets. Additionally, hardness was higher at 90 and 120 kg·m-3 densities in bled fillet compared to 150 kg·m-3. The first three days of storage showed a higher oxidation rate in unbled fillets than in bled fillets, confirming the contribution of hemoglobin to oxidation development with different mechanisms of protein oxidation. The obtained results revealed the same fillet quality in all aspects at either 90 or 120 (kg·m-3) stock densities, which would suggest 120 kg·m-3 for the fishery industry. However, higher stocking density in this study would not be appropriate for fish welfare.

Fin damage and growth parameters relative to stocking density and feeding method in intensively cultured European perch (Perca fluviatilis L.).

We evaluated the relationship of stocking density to survival, growth performance and fin condition of European perch Perca fluviatilis with hand feeding and self-feeders. Hand-fed perch (body weight 19.1 ± 5.1 g and total length 107 ± 9 mm) were reared at 0.5, 1.0, 1.5 and 2.0 fish/L. Self-feeding perch (body weight 25.4 ± 3.9 g and total length 128 ± 7 mm) were reared at stocking densities of 0.6, 1.0 and 1.4 fish/L. Pond-reared perch served as a comparison group for fin damage assessment. We found no differences in survival rate among stocking densities with either feeding method. Hand-fed fish displayed the highest weight gain and SGR at stocking density of 0.5 fish/L. The self-feeding fish showed a non-linear association of weight gain with stocking density with the highest growth at 1.0 fish/L. Fin length was noticeably greater in pond-reared fish compared with RAS-reared fish regardless of feeding method. In both experiments, fin length relative to standard length showed a negative relationship with stocking density, with pectoral fins showing the greatest effect. Fin condition deteriorated with increasing stocking density, and growth was highest at 0.5 and 1.0 fish/L in hand-fed and self-feeding fish, respectively.

Ultrastructural feature of spermatogenic cells and spermatozoon in cultured burbot Lota lota.

Testis development and ultrastructure of spermatogenic cells and spermatozoa of burbot Lota lota, a commercially important cold freshwater fish, were studied by light and transmission electron microscopy. Spermatogonia, spermatocytes, spermatids, and spermatozoa are distributed along the seminiferous tubules. Electron-dense bodies appear in germ cells from primary spermatogonia to secondary spermatocytes. We identified three distinct stages of spermatid cell differentiation based on chromatin condensation, development of the flagellum, formation of a nuclear fossa, and elimination of excess cytoplasm. Spermatozoa were anacrosomal and characterized by location of the centrioles outside the nuclear fossa and incomplete perpendicular arrangement of the centrioles. The sperm flagellum displayed an axoneme with nine doublets of peripheral microtubules and two central microtubules. These results provide valuable information for burbot taxonomy and may clarify the process of spermatogenesis for this species.

Efficacy of different anaesthetics for pikeperch (Sander lucioperca L.) in relation to water temperature.

OBJECTIVES: The objectives of the study were to compare the different doses of clove oil, Propiscin, and tricaine methane sulphonate (MS 222) in relation to water temperature in pikeperch aquaculture. DESIGN: For assessment of this experiment 168 fish (10.77 ± 0.59 cm total body length and 7.88 ± 1.74 g body weight) were used. Three different anaesthetic treatments (Propiscin, clove oil and MS 222) were used. Three doses of each anaesthetic treatment (Propiscin: 0.5; 1; 1.5 ml x L(-1), clove oil: 15; 30; 60 mg x L(-1), MS 222: 50; 100; 150 mg x L(-1)) were compared at three different temperatures 9.5; 15.5 and 23 degrees C. RESULTS: In comparison of these doses of anaesthetic in different temperature, the significantly shortest time to attain phase A7 (total complete anaesthesia) was observed for Propiscin (1.5 ml L(-1)) 0:31 ± 0:04 min (23 degrees C) to 0:33 ± 0:25 min (9.5 degrees C) compared to MS 222 (150 mg x L(-1)) 1:04 ± 0:21 min (23 degrees C) to 1:54 ± 0:32 min (9.5 degrees C) and clove oil (60 mg x L(-1)) 1:05 ± 0:17 min (23 degrees C) to 3:05 ± 0:31 min (9.5 degrees C). On the other hand, the longest time of anaesthesia recovery was attained using Propiscin (1.5 ml x L(-1)) 10:35 ± 1:40 min (23 degrees C) to 32:30 ± 1:10 min (9.5 degrees C) compared to clove oil (60 mg x L(-1)) 2:39 ± 0:50 min (23 degrees C) to 9:36 ± 2:34 min (60 mg x L(-1), 9.5 degrees C) and MS 222 (150 mg x L(-1)) 2:26 ± 1:27 min (23 degrees C) to 4:59 ± 0:39 min (9.5 degrees C). CONCLUSIONS: The results from this study showed that the optimal and sufficient doses in all tested temperatures for pikeperch are 30 mg x L(-1) of clove oil, 100 mg x L(-1) of MS 222 and 0.5 ml x L(-1) of Propiscin.

Effect of chronic exposure to prometryne on oxidative stress and antioxidant response in common carp (Cyprinus carpio L.).

The effects of the triazine herbicide prometryne, commonly present in surface and ground waters, on oxidative stress and antioxidant status of common carp (Cyprinus carpio) were investigated. Fish were exposed to sublethal concentrations of prometryne (0.51, 8, and 80µg/l) for 14, 30, and 60 days. Activity of superoxide dismutase (SOD), catalase (CAT), and glutathione reductase (GR), as well as levels of thiobarbituric acid reactive substances (TBARSs) were assessed in brain, gill, intestine, liver, and muscle. After 14 days exposure, decreased GR activity in brain was observed for all prometryne-exposed groups compared with the controls. Changes were observed in SOD activity in brain and gill after 30 days in all exposure groups. Changes in CAT activity were observed only at the highest concentration (80µg/l) in liver and intestine after 60 days. The observed effects on carp antioxidant systems may be a defense against oxidative damage. The study demonstrated changes in antioxidant parameters and the importance of evaluating the potential long-term risk to fish of prometryne, at environmentally realistic concentrations (0.51µg/l). The results suggest that antioxidant responses may have potential as biomarkers for monitoring residual triazine herbicides in aquatic environments.

Anti-androgen vinclozolin impairs sperm quality and steroidogenesis in goldfish.

In mammals, vinclozolin (VZ) is known as anti-androgen, which causes male infertility via androgen receptor (AR) antagonism. In aquatic animals, the VZ effects on reproductive functions are largely unknown and results are somewhat contradictory. To understand VZ adverse effects on male reproduction, mature goldfish (Carassius auratus) were exposed to three nominal VZ concentrations (100, 400, and 800 µg/L) and alternations in gonadosomatic (GSI) and hepatosomatic indices (HSI), 17ß-estradiol (E(2)), 11-ketotestosterone (11-KT) and sperm quality were investigated compared to the solvent control. One group was exposed to E(2) (nominal concentration of 5 µg/L), an estrogenic compound, as a negative control. Following one month exposure, GSI and HSI were unchanged in all VZ treated groups compared to solvent control. Sperm volume, motility and velocity were reduced in fish exposed to 800 µg/L VZ. This was associated with the decrease in 11-KT level, suggesting direct VZ effects on testicular androgenesis and sperm functions. In goldfish exposed to 100 µg/L VZ, 11-KT was increased but E(2) remained unchanged. This is, probably, the main reason for unchanged sperm quality at 100 µg/L VZ. In goldfish exposed to E(2), GSI and 11-KT were decreased, E(2) was increased and no sperm was produced. The present study shows different dose-dependent VZ effects, which lead to impairment in sperm quality via disruption in steroidogenesis. In addition to VZ effects through competitive binding to AR, our data suggests potential effects of VZ by direct inhibition of 11-KT biosynthesis in fish as well as abnormalities in sperm morphology.

Comparison of the effects of four anaesthetics on haematological and blood biochemical profiles in pikeperch (Sander lucioperca L.).

OBJECTIVES: The objectives of the study were to compare the effects of Propiscin, 2-phenoxyethanol, clove oil and tricaine methane sulphonate (MS 222), anaesthetics frequently used in aquaculture. DESIGN: The haematological and biochemical blood profiles of pikeperch (Sander lucioperca L.) anesthetized with Propiscin (1.5 ml L-1), 2-phenoxyethanol (0.3 ml L-1), clove oil (33 mg L-1), MS 222 (150 mg L-1) and non-anesthetized control group were tested. Each tested group was divided into two subgroups, the first subgroup was sampled in anaesthesia 10 min after application of the anaesthetic and the second one live on 24h. RESULTS: The erythrocyte count and haematocrit was significantly decreased in 2-phenoxyethanol (24 h) compared with control group (CG). The mean corpuscular haemoglobin concentration was significantly increased in 2-phenoxyethanol (10 min), Propiscin (10 min and 24 h) compared to CG. The 2-phenoxyethanol (10 min and 24 h), MS 222 (24 h), clove oil (24 h), and Propiscin (10 min and 24 h) showed significantly lower leukocyte count compared with CG. The level of glucose was significantly (p<0.05) elevated with MS 222 (10 min) and clove oil (10 min) compared with CG. The 2-phenoxyethanol (10 min and 24 h), MS 222 (24 h), clove oil (24 h), and Propiscin (24 h) showed significantly lower (p<0.01) ammonia levels compared with CG. The triacylglycerols was significantly decreased (p<0.01) with Propiscin (10 min and 24 h), MS 222 (24 h), clove oil (24 h) and with 2-phenoxyethanol (24 h) compared with CG. After 24 hours MS 222 (24 h) and Propiscin (24 h) anaesthesia, fish showed significantly lower (p<0.01) concentration of inorganic phosphate compared with CG. CONCLUSIONS: On the basis of this experiment, it appears that clove oil was associated with the lowest effects in pikeperch and therefore would be recommended as an alternative to MS 222, while Propiscin and 2-phenoxyethanol are not suitable for manipulation with pikeperch in aquaculture.