THE FISH IN LAKE MAGADI 
95 
THE FISH IN LAKE MAGADI 
By C. W. Woodhouse 
In the shallow soda springs which feed Lake Magadi there 
are found some small fish which have been identified by Mr. 
Boulenger of the British Museum as Tilapia mossambica. 
They were discovered by Mr. F. W. Graham and were stated 
by Mr. Boulenger to be immature. 
These fish were observed and studied again in the month 
of December 1911, by the present writer, and were found at 
that time to be breeding, ova and fry in all stages of 
development being secured. 
The habitat of these fish is interesting. 
Lake Magadi is situated in a depression of the Bift Valley 
at an altitude of about 2,000 ft. The surrounding country 
is arid and waterless for a long way on each side of the lake. 
The nearest actual water is the Southern Guaso Nyiro River 
situated on the west of the lake, some fifteen miles from the 
springs on the east side of the lake where the fish occur. 
The springs on the east side come out from under the 
cliffs which surround the lake and flow over the silica and into 
the mother liquor of the soda itself. This water is highly 
charged with soda and averages a depth of from one to three 
inches. The fish appear to congregate as near the origin of 
the water as possible, although they are not averse to going 
someway down towards the soda itself. 
The composition of the water is as follows : — 
The solids are principally sodium carbonate with traces 
of magnesium carbonate, sodium chloride and sodium 
bicarbonate. Shade temperature, 9.30 a.m., 92°F. 
It is a physical impossibility for the first occurrence of 
these fish to have been water-borne, as their situation in regard 
to the neighbouring country precludes this, unless they are 
survivors (who have taken to shallow water) of the period when 
Lake Magadi was not solid or comparatively so. Should this 
be the case, they will probably be found to have developed 
local variations. 
Vol. II.— No. 4. 
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