Charles Darwin, ichthyology and the species concept

This contribution presents the ichthyological writings of Charles Darwin (1809–1882), by periods, viz. ‘the years prior to the voyage of the Beagle’ (about 1825–1830); ‘the Beagle years’ (1831–1836); ‘from the return of the Beagle to the Foundation of Origin’ (1837–1844); and ‘the mature Darwin’ (1845–1882). Overall, this material covers 45 000 words penned by Darwin, but represents only 0.7% of his lifetime output of about 6 million words, indicating a limited interest in fish. However, this sample, briefly described here, but analysed in great detail in a forthcoming volume on Darwin's Fishes, allows drawing inferences on Darwin's working style that were missed in conventional biographies. On the other hand, it is suggested, based on a close reading of the 6^th (1876) edition of Origin, that Darwin was not particularly interested in the theoretical issues now associated with the species concept, nor indeed with other levels of the Linnean system.     

Aquaculture: The legal framework: Bruce H. Wildsmith. Emond-Montgomery Ltd., Toronto,Canada, 1982, 313 pp. U.S. $ 45.00, ISBN 0-920-722-08-3

In the present communication the gross symptoms of severe riboflavin deficiency are reported as observed in six experiments conducted with four independent stocks of rainbow trout fry and fingerlings. Unlike other reports on salmonids, ocular opacities were infrequently observed, and neither their rate of incidence nor their severity was related to dietary riboflavin content. Compared with both satiety-fed and pair-fed controls, riboflavin-deficient trout exhibited lethargy, apparent muscular weakness, reduced appetite and growth rate, severe fin erosion (all fins), rapid opercular movements, light greenish-yellow skin coloration and high mortality rate. These symptoms, although due to riboflavin deficiency per se, are nonspecific. As the cataracts produced by others in riboflavin-deficient trout appear to be a specific, diagnostic symptom, it is important to identify those conditions which can preclude their development in riboflavin deficiency.