The Effect Of Birbira Milletia Ferruginea (hochst.) Baker On Some Barbus Spp. (cyprinidae Teleostei) In Gumara River (lake Tana) Ethiopia

To assess the possible effect(s) of birbira, Milletia ferruginea (Leguminosae) on the barbs,rnBarbus spp. (Cyprinidae) from Gumara River (Ethiopia), aquarium and field study wasrnconducted during August to September, 2002. The effects of birbira at concentrations of 0.02,rn0.04, 0.1, 0.2, 0.3 and 0.4 g/l were studied to conduct experiments on different species, sizesrnand sexes of fish. The amount of crude powders of birbira seeds actually applied by thernfishermen at Dukalit stream (a tributary of Gumara River) was estimated to be about 0.4 grnper liter of water. This amount was found to be excessive as only 0.02 g/l (a 5% dilution) wasrnenough to bring about total fish kills in about an hour. It was observed that the amount ofrnoxygen in the birbira solution remained almost intact after all of the fish died, supporting thernidea that rotenone does not deplete oxygen dissolved in the water but affects mechanism ofrnoxygen uptake by fish. The findings of the study revealed that when using birbirarnconcentrations of 0.02 to 0.4 g/l, all of the fish died in about 30 to 60 minutes. Comparison ofrndifferent species showed that B. brevicephalus and juvenile ‘large’ barbs (weighing < 50 g)rnhad relatively better tolerance than had another close relative, Varicorhinus beso of similarrnweight. Female B. brevicephalus (usually ≥ 100 g) with running (ripe) gonads of tolerated thernpoison better than their male (usually < 100 g) counterparts. Fertilized eggs, presumed tornhave been spawned by B. brevicephalus, were collected from Dukalit stream and poisonedrnwith 0.4 g/l birbira for 15 minutes, and then incubated in clean water. None of these eggsrnhatched while all of the controls (unpoisoned eggs) did after 3 days of collection from thernriver. The findings of this study are believed to lay a basis for further research andrnconsequently to solve problems related to poisoning fish with birbira and/or other herbs on Gumara River and other waters.rnKey words/phrases: birbira (Milletia ferruginea); Gumara River (Lake Tana); ‘large’ Barbusrnspp.; survival time.

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