Microbiological and thin-layer chromatography-bioautography (TLC-B) procedures were undertaken to assess the residues of some chemotherapeutic reagents consisting of oxytetracycline (OTC), chlortetracycline (CTC), flumequine (FLM) and trimethoprim+ sulphadimidine (TMP+SUL) in the sera and tissues of common carp (Cyprinus carpio) and rainbow trout (Oncorhynchus mykiss ). Treatment of carp as a bath (200ppm) and rainbow trout by mouth (8Omg.kgb.w.) with OTC resulted in kidney levels of lOug/g, and 4.41ug/g, respectively, No antibiotic residue of OTC was detectable in both liver and muscle of both species of fish. Treatment of carp as a bath (200ppm) with TMP+SUL resulted in a detectable levels of the drugs in sera and kidney of the fish. Oral treatment (l0mg/kgb.w.) of rainbow trout with FLM resulted in the drug levels of 2.37mg/mi, 3.18g/g and 2.051ug/g in sera, muscle and liver-kidney of fish, respectively whereas no drug level was detectable in the sera and tissues of carp treated as a bath (200ppm). Similar results were obtained using TLC-B procedure. However, using this method the residues of these chemotherapeutic reagents were detectable for a longer period than bioassay tests. Also using TLC-B, a combined treatment (l.P) of these species of fish with the above drugs was not successful for detect the drugs residues.
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