The influence of sex, source (pond and wild) acclimation and health status on some blood parameters of C. gariepinus was studied. There were no significant differences between the blood parameters (haemoglobin (Ht), packed cell volume (PCV), erythrocyte sedimentation rate (ESR), red blood cells (RBC), RBC indices ( MCHC;, MCH: and MCV), white blood cells (WBC) and differential counts (neutrophils, lymphocytes, basophils and eosinophils) of the males and females among the apparently healthy and sick group of fish under sex, source and acclimation. Differences in blood parameters in fish before and after acclimation were noted in the WBC (p<0.001), neutrophils (p<0.001) and lymphocytes (p<0.001). Interactions between sex, acclimation and health status did not significantly influence all the parameters studied; however, various degrees of significant differences were produced by the interactions of health status and source of fish in the WBC (p<0.05), neutrophils (p<0.001), lymphocytes (p<0.001) and monocytes (p<0.05). Pooled data for males and females, apparently healthy and sick fish, respectively, showed there were significant differences between the WBC, neutrophils and lymphocytes of males and females under acclimation as well as monocytes of apparently healthy and sick fish under source and neutrophils of the same under acclimation. Results from this study suggest that sex, source of fish, and period of acclimation have some degrees of influence on the blood parameters of C. gariepinus and hence the need to reckon with them when reporting haematological parameters of this fish species.

The purpose of this work was to investigate the size-relative effectiveness of clove oil as an anaesthetic for rainbow trout and goldfish. In total, 128 rainbow trout (Oncorhynchus mykiss) (two groups of 20-23 and 30-33 cm mean fork length) and 160 goldfish (Carassius auratus) (four size groups of 1.5-2.5, 5-7, 11-15 and 20-25 cm) were anaesthetized at different clove oil concentrations of 50, 100, 150 mg·l -1 for trouts and 75, 100, 150 mg·l -1 for goldfish. Rainbow trout exhibited total loss of balance and no response to external stimuli with shorter induction time as dosage increased (120.5 s, 64.4 s and 44.3 s, respectively). Goldfish exhibited total loss of balance and no response to external stimuli after induction time that varied with dosage used and body size of fish. The small fish (1.5-7 cm) exhibited shorter induction time which ranged from 84.28 s at 75 mg·l -1 clove oil to 41.14 s at 150 mg·l -1 clove oil. The larger fish had a longer induction time inversely related to the dosage. Recovery time was longer than induction time in both species. Both species recovered within 6 min after anaesthesia at 150 mg·l -1 clove oil. Clove oil did not produce marked changes (P < 0.05) in the physiological indicators of goldfish compared to the control. However, marked changes (P < 0.05) were exhibited in the haematocrit of treated rainbow trout that also exhibited hyperkalaemia and hyperglycaemia (P > 0.05). For both fish species, clove oil was effective, producing minimum stress and zero mortalities, and can be recommended as an effective anaesthetic. Syzygium aromaticum, fish anaesthesia, animal welfare

AbstractsHeterobranchus bidorsalis (mean length 31.50±2.32cm SD; mean weight 241.25± 30.39g SD) was exposed to cypermethrin (0.0005, 0.0075, 0.010, 0.125 and 0.0150ppm)

This trial was conducted to assess the possibility of replacing maize (Zea mays L) with varying levels of whole cassava (Manihot esculent crantz) root meal (WCRM) in the diet of hybrid catfish (Heterobranchus, bidorsalis x Clarias gariepinus). The effect of replacement on growth variables and nutrient utilization of the WCRM as a replacement for maize were also determined. Four practical diets with varying replacement levels of maize at 0 (A o), 33 (B 33), 66(C 66), and 100% (D 100) were formulated and fed to hybrid catfish fingerlings for 32weeks. Fish were fed twice daily at 5% body weight/day. Optimum growth, nutrient utilization of the fish were assessed. The results obtained from the study indicated that WCRM can completely replace maize with the best result at 66% inclusion. The highest values of growth performance were: final weight 12,782±601.21g, mean weight gain 12041.43±312.66g, and daily weight gain 78.78±10.28g. The nutrient utilization indicated the best feed conversion ratio (FCR) 1.71±0.40; Gross feed conversion efficiency (GFCE), 68.95±5.161; protein intake (PI), 12975.88±306.11g, protein efficiency ratio (PER) 1.98±0.11; and nitrogen metabolism (NM) 10782.98±314.12g/100g were recorded in diet C 66. However, growth and nutrient utilization variables varied significantly (p<0.05) within the treatment period. The mean final weight, FCR and PER of the fish fed trial diets were not significantly different (p>0.05) from the control value. Dietary WCRM at 100% inclusion produced similar results in the mean weight gain (MWG), mean daily weight gain (MDWG), Gross Feed Conversion Efficiency (GFCE), Protein Intake (PI), and survival as the control diet. It could therefore be concluded that WCRM can replace maize in the diet of hybrid catfish effectively up to 100% with the optimal performance at 66% level of inclusion. Fish farmers can therefore explore the use of WCRM as an alternative to maize meal in hybrid catfish diet with better profit margins.

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