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Among the Lake Tana large barbs of about 10 cm SL only representatives of the ' acute ' morphotype can be distinguished, in the size range 10-20 cm SL ' bigmouth big eye ' can be identified also. As for the rest, very few individuals can be confidently affiliated with a particular morphotype most of them looking like ' intermedius '. Even within the range of 20-30 cm SL some individuals are still difficult to identify. Principal component analysis of cranial characters revealed discrete groups of morphotypes. Differences in both external and cranial characters of the morphotypes result from divergence which is most pronounced when fish are 4-5 years old and 20-25 cm SL. This divergence cannot be related exclusively with differences in the growth rates of individuals representing different morphotypes. Differences in food composition between the morphotypes probably increase in parallel with their morphological divergence. Differences between the morphotypes in the lateral line (ll) and the gill rakers (Sb) counts were revealed using ANOVA. Comparison of the Lake Tana Barbus complex of forms with that previously known from Lake Lanao (Philippines) suggests that in both lakes the different forms arose sympatrically but that sympatric speciation in Lake Lanao has advanced further than in Lake Tana. 1996 The Fisheries Society of the British Isles

During the rainy season (September-November 1994), in tributaries of Lake Tana (Ethiopia), the Gumara, Gelda and Negashu, barbs of different morphotypes were ready to spawn, running and spent. The most numerous were barbs similar to Barbus intermedius common in many rivers of the Ethiopian Highlands. They were also found spawning in the Gumara and Gelda Rivers in the dry season (February 1996(February , 1997. There were no evident differences in time and place of spawning of barbs representing different morphotypes. Only zurki, bigmouth mini-eye and bighead were not found in the rivers. Spatial and temporal segregation may contribute to reproductive isolation of morphotypes spawning in rivers, but if reproductive isolation exists the main role must be played by differences in mating behaviour. Morphotypes of the Lake Tana barbs have different migration patterns. Barbs similar to the riverine B. intermedius may spend their lives in rivers or in the lake, moving to and fro. Barbs of acute, bigmouth big-eye and, perhaps, other morphotypes migrate downstream as alevins or fry, stay in the lake for several years and migrate back into rivers for spawning after reaching maturity. 1999 The Fisheries Society of the British Isles

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Four fish species, Pollimyrus isidori (Mormyridae), Barbus paludinosus, Labeo forskalii (Cyprinidae), and Nemacheilus abyssinicus (Balitoridae), new to the Omo-Turkana basin, were recorded from the Gojeb River, a tributary of the Omo River (south-western Ethiopia) . Occurrence of the latter species in the upper reaches of the Blue Nile and of the Omo drainage substantiates the belonging of the upper parts of these water systems to the Abyssinian highlands ichthyofaunal province . 125

The study of the composition of fatty acid markers of tadpoles of cohabiting amphibian species for the first time revealed differences in their diets: the moor frog Rana arvalis prefers bacteria not associated with plant detritus, whereas the diet of the common spadefoot Pelobates fuscus is based on cyanobacteria, green algae, diatoms, and possibly higher plants. Major differences in the fatty acid composition are determined by the difference in the percentage of eicosapentaenoic and myristic acids.

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