The present study was carried out from 346 skulls of Praomys jacksoni (Muridae) captured in some forest areas of the surroundings of Kisangani city (island, right and left banks of Congo River) from 1994 to 1999). The results obtained from twenty-five skulls measurements revealed the diversity existing inside each population studied. The sexual dimorphism is favorable to males for seven measurements (GRLE, HEBA, DIA1, DIA2, INT, LNAS, and LOTE) whereas eighteen remain stable. The skulls of insular populations (Tundulu and Mbiye) are bigger than those of the forest reserves ( Masako and Yoko) for twenty measurements: GRLE, PRCO, HEBA, HEPA, DIA1, DIA2, INT, ZYPL, PAL, UPTE, UPDE, M1, BNAS, LNAS, BUL, DIN, HRZ, ROH, ROB and PCPA The skulls of Mbiye island populations are bigger than those of Tundulu island for eighteen measurements (GRLE, PRCO, HEBA, HEPA, PAF, DIA1, DIA2, ZYG, UPTE, UPDE, M1, ZYPL, BNAS, LNAS, LOTE, CHOA, DIN, PCPA). The skulls of populations from the left bank (Yoko forest reserve) are bigger than those of the right bank for six measures (GRLE, HEBA, DIA1, INT, CHOA and PAF). These results indicate that craniometrical measurements of the adult animals are stable and constitute a complementary means for identifying the species in the Praomys genus. The variations observed with certain examined characters would be the consequence of the biological phenomenon of speciation. It is thus desirable that molecular studies are carried out on these muridae in order to validate this hypothesis.
Food and feeding habits of Hippopotamyrus psittacus (Boulenger, 1897; Pisces: Mormyridae) of Congo river has been undertaken from February to July 2007 by the stomach contents analysis. 44 H. psittacus ranging from 55 to 320 mm of length were captured in the Congo River (Wagenia Falls and Kikongo beach). The total length, the standard length and height of the body were measured with a ribbon meter and weighed using both bood scales of 0- 3000gr. Afterward, stomach contents were taken and conserved in the Laboratory for future analysis. Stomachs contents were examined using a binocular magnifying glass LEICA WILDHEERBRUGG Mg model with a magnification of 10 to x50. The stomachs contents analysis showed that H. psittacus is a carnivorous with an insectivorous tendency by feeding mainly on aquatic insects and other animals remnants. On the other side, the food regime of H. psittacus appeared more diversified during the relatively dry season periods. On the same way, the average stomach contents weight indicates that the feeding activity is more or less different during different season periods with an increasing feeding activity during the relatively dry season periods.
A study was conducted on the food ecology of Ichtyoborus besse congolensis of Biaro River and its Yoko tributary in the Yoko Forest Reserve, Democratic Republic of the Congo. It took place over a period of one year: from September 2008 to August 2009. The size and weight of 98 specimens of Ichtyoborus besse congolensis Giltay, 1930 sampled varies from 3.6 to 31.5 cm, with an average of 21.5 cm for the first parameter and of 14-364.4 g, that is, an average of 77.4 g for the second measurement. The analysis of 68 full stomachs of Ichtyoborus besse congolensis Giltay, 1930 under a dissecting microscope shows the dominance of animal origin preys with more or less 6 taxa against some traces of plant fragments. The composition of the diet according to seasonal periods, showed that during relatively dry seasonal period, males appeared to be fish (OCC = 9.6), Heteroptera (OCC = 3.2), Ephemeroptera (OCC = 3.2) and plant fragment eaters (OCC = 3.2), while the trace of molluscs is observed only in females (OCC = 33.3). Shrimps, fins and scales were found in both sexes, but in different proportions, because the large proportion of shrimps was observed in males (OCC = 83.9) while those of fins and scales were dominant in females. More, the emptiness rate was significant only in males. On the other hand, during the rainy season period, females become more opportunist in fish (OCC = 50), shrimps (OCC = 100), fins (OCC = 25) and scales (OCC = 50) than males with respectively 16.6 %, 76.6%, 6.6% and 36.6% of occurrence, and the rate of emptiness is higher in females. The food index (FI) and index of relative importance (IRI) of the main categories of preys; preys with high percentages are respectively fish (44%), shrimps (29%), animals fragments (26%). All the other categories of associated preys represent only 1%. It is the rainy period which offers many favorable opportunities for a good growth of fish species.