Xenobiotic excretion in fish with aglomerular kidneys

Foreign chemicals in teleost fish are primarily excreted via urine and bile. Xenobiotics and their metabolites excreted via urine are filtered in the glomerulus and/or secreted by tubular transport within the kidney. Contrary to most fish species, such as the Atlantic cod Gadus morhua, the polar cod Boreogadus saida displays a complete absence of the glomerular apparatus. We examined the excretory routes in an aglomerular (B. saida) vs a glomerular (G. morhua) gadoid fish. Using an inert polysacharride as a model compound, it is demonstrated that this xenobiotic is excreted solely via the urine in G. morhua and via the bile in B. saida.