Article — Artikel Provisional clinical chemistry parameters in the African Sharptooth catfish (Clarias gariepinus) J G Myburgha*, C J Bothaa, D G Booyseb and F Reyersc reported in fish in other parts of the ABSTRACT world2,18. Controlled laboratory exposure Pollution affects aquatic systems worldwide and there is an urgent need for efficient of Sharptooth catfish to copper concen- monitoring. Fish are generally sensitive to their environment and are thus considered to trations that were measured in the be valuable bioindicator species. The African Sharptooth catfish (Clarias gariepinus)is Olifants River, Kruger National Park, sig- particularly important in this respect because of its very wide distribution. In order to use nificantly altered their blood chemistry C. gariepinus as a bioindicator species its baseline clinical chemistry must be defined. parameters19. Existing data are scarce, and the objective of this work was therefore to establish clinical Given its wide distribution, the African chemistry parameters for Blood was collected from male and female catfish C. gariepinus. Sharptooth catfish could be a suitable and a number of clinical chemistry parameters were determined. Plasma protein values, bioindicator of pollution in a variety of but particularly those of plasma albumin, were found to be very low,approximately half the value for dogs, but similar to the values in Channel catfish (Ictalurus punctatus). Plasma urea freshwater aquatic ecosystems. However, values in Sharptooth catfish were found to be much lower than in dogs, but only marginally to be able to detect molecular and cellular lower than in Channel catfish. Plasma creatinine in Sharptooth catfish, however,was only a level changes in response to pollutants, quarter of that of dogs and one third of that found in Channel catfish. These findings may prior knowledge of physiological baseline 5 have implications for using urea and/or creatinine as an index of renal glomerular filtration, parameters is essential . There is, unfortu- as is done in mammals. Plasma enzyme activity ranges were much lower in Sharptooth nately, a dearth of information on the catfish than in dogs, particularly for alkaline phosphatase (ALP) and alanine amino- clinical chemistry of the African Sharptooth transferase (ALT). By comparison, Channel catfish have an even lower ALT activity range catfish. The objective of this paper is, but an ALP range that is very similar to dogs. The implications for using these enzymes as therefore, to define baseline clinical markers for liver disease are not clear from these data, as factors such as plasma half-life and chemistry parameters of C. gariepinus that tissue distribution remain to be determined. The very low plasma thyroxine (T4) levels have could be used as indicators of organ func- important implications for laboratory personnel, who will have to set up calibration and tion or damage, to assess the impact of standardisation adaptations for the methods that are generally designed for human pollution in aquatic ecosystems. samples. Although the sample size was too small for reliable comparisons, it appeared that there was little difference in the parameters measured between male and female fish. The MATERIALS AND METHODS values obtained are a useful starting point for using C. gariepinus as a bioindicator species. Key words: bioindicator, Clarias gariepinus, clinical chemistry, plasma enzymes, proteins, Experimental animals and facilities renal function, Sharptooth catfish, thyroxine, T . 4 Male (n = 13) and female (n = 15) African Myburgh J G, Botha C J, Booyse D G, Reyers F Provisional clinical chemistry parameters in Sharptooth catfish (Clarias gariepinus) the African Sharptooth catfish (Clarias gariepinus). Journal of the South African Veterinary with body mass ranging from 600–1000 g Association (2008) 79(4): 156–160 (En.). Department of Paraclinical Sciences,Faculty of Veteri- were obtained from an earth dam at the nary Science, University of Pretoria, Private Bag X04, Onderstepoort, 0110 South Africa. University of Pretoria experimental farm. The fish were kept indoors in a 1500 tank containing municipal water. An external INTRODUCTION is one of the most important individual filter system was used to constantly circu- Aquatic ecosystems are subject to pollu- species in traditional freshwater fisheries late the water. The filter system was tion that may have dire effects3,18. Deleteri- in Africa15. It is widely distributed in Africa, cleaned and at least a third of the water in ous effects of pollution are often preceded where it occurs in almost any freshwater the tank was replaced every week. by subtle molecular and cellular changes habitat, but favours floodplains, large Commercial trout pellets were fed that can be detected in some inhabitants sluggish rivers, lakes and dams15. The fish 3 times a week. of these ecosystems5,12,19. Fish are suitable is omnivorous, feeding on fish, birds, bioindicator animals because they respond frogs, small mammals, reptiles, snails, Collection of samples with great sensitivity to changes in the crabs and other invertebrates. It is also After a depuration period of 1 month aquatic environment3,14,18,19. capable of feeding on seeds and fruit15. the fish were netted, removed from the The Sharptooth catfish (Clarias gariepinus) Numerous chemical pollutants have holding tank and placed in a lateral posi- been detected in tissue samples from tion. Fish were not anesthetised for blood aDepartment of Paraclinical Sciences, Faculty of Veteri- nary Science, University of Pretoria, Private Bag X04, Sharptooth catfish collected in South collection. Blood was collected from the Onderstepoort, 0110 South Africa. Africa7. Anatomical and histological ab- central vein, located just below the spinal bDepartment of Anatomy and Physiology,Faculty of Veter- normalities of the reproductive organs cord, caudal to the cloaca and using the inary Science, University of Pretoria, Private Bag X04, Onderstepoort, 0110 South Africa. have been observed in Sharptooth catfish lateral line as reference point. The blood cDigital Veterinary Diagnostics, PO Box 41468, Gars- collected from the Rietvlei and Marais was collected with heparinised (Heparin fontein East, 0060 South Africa. Dams near Pretoria, South Africa1. These sodium-fresenius, Intramed) 2 m sy- *Author for correspondence. E-mail: [email protected] aberrations were similar to those attributed ringes (Omnifix 2 m , B Braun Melsungen Received: March 2007. Accepted: November 2008. to chronic exposure to aquatic pollutants AG) and 22 G needles (22GX1½’, Terumo). 156 0038-2809 Tydskr.S.Afr.vet.Ver. (2008) 79(4): 156–160 Table 1: Summary of the Sharptooth catfish clinical chemistry data (95 % confidence and/or 2.5 to 97.5 % percentile reference ranges). Approximate normal / Non-normal data distribution or Sexual difference Gaussian data data unable to be normalised by log-transformation Parameter Units Lower Mean Upper Lower Median Upper Difference P-value P-value 95 % CL 95 % CL 2.5 % 97.5 % t-test Willcoxon percentile percentile equal var. Rank Length mm 430 550 660 NS 0.190 TPP g/ 30.8 46.2 61.6 NS 0.799 ALB g/ 8.1 12.35 16.7 Sig 0.036 GLOB g/ 21.8 33.1 44.4 NS 0.670 A/G ratio 0.21 0.37 0.54 Sig 0.014 ALT U/ 0 12.7 29 NS 0.345 ALP U/ 0.1 2.3 52 NS 0.849 AST U/ 0 117 285 NS 0.700 CK U/ 200 2370 28052 NS 0.888 GGT U/ 0 6.6 15.0 Sig 0.004 LD U/ 0 450 878 NS 0.959 HBD U/ 0 131 306 NS 0.597 GLD U/ 0 17 55 NS 1.000 T Bil µmol/ 4.4 16.4 38.7 NS 0.919 Urea mmol/ 0.3 1.9 3.4 NS 0.442 Creat µmol/ 0.0 20.5 29.0 NS 0.643 T4 nmol/ 0.0 4.5 7.5 NS 0.642 NS = no significant difference between male and female group data (P ≥ 0.05). Sig = significant difference between male and female group data (P < 0.05). The blood was transferred to lithium hep- using Randox reagents (Randox Labora- allowable D’Agostino limit for skewness), arin blood collection tubes (BD tories) (optimised DGKC recommended the data were subjected to a logarithmic Vacutainer, Becton, Dickinson and Com- method). α-Hydroxybutyrate dehydro- transformation and the transformed pany) immediately after collection. Blood genase (HBD) was determined on an data re-tested for normality. was centrifuged at 1500 g, the plasma col- automated clinical chemistry analyser • Where the logarithmic transformation lected and frozen in sterile vials (1.8 m (Roche/Hitachi Modular Analytics) (opti- did not yield a good approximation of cryotube vials, Nunc A/S). Samples were mised DGKC recommended method). normality or when the D’Agostino submitted to the Clinical Pathology Labo- All enzyme activity assay results were criterion for kurtosis was exceeded, ratory, Faculty of Veterinary Science, Uni- obtained at 37 °C. Total thyroxine (T4) was non-parametric statistical methods (vide versity of Pretoria for analysis. determined using a Coat-A-Count Total infra) were then applied to those data. 125 T4 solid phase Iodine Radioimmuno- • The reference interval (range) for those Clinical chemistry assay kit (Siemens Medical Solutions data that met the criteria for approxi- The NExCT™ clinical chemistry system Diagnostics). Radioactivity was measured mate normality (both untransformed as (Schiapparelli Biosysytems) was used to by an Auto-Gamma 5000 Series Gamma well as log-transformed) was based on quantify total plasma protein (TPP) Counting system. Owing to sample the 95 % confidence limit for 26 observa- (Biuret principle of Weichselbaum), total quality and/or availability, only 15 sera tions (mean ± 2.056 SD). bilirubin (T Bil) (van den Bergh diazo (8 from male fish sand 7 from female fish) • The reference intervals (ranges) for data principle), albumin (ALB) (BCG dye- were assayed. that were non-normal (even after log- binding method) and urea (enzymatic UV transformation) were calculated accord- method) using NExCT™ reagent kits.