220 / TREUBIA VOL. II, 2—4. 
“Shortly after the letting in of the water duck-weed is formed in nearly 
“all the ponds if fresh water also can enter, and on a clay-soil if only 
“sea-water gets in. On soils mixed with sand or gravel the duck- 
“weed (ganggeng) has more difficulty in developing than on clay, and 
“does not develop at all unless there is also an admixture of fresh water’’. 
In the “Synopsis of the Section-reports on the results of the inquiries 
into the pisciculture and fisheries in the Residency of Pasuruan” (Samen- 
trekking van de Afdeelingsverslagen over de uitkomsten der onderzoekingen 
naar de vischteelt en visscherij in de Residentie Pasoeroean (!%)) of the 
“Prosperity-commission” (Welvaart-commissie), page 16 reads: “The produc- 
“tivity of many ponds has of late years declined, which is attributed by the native 
“population to the circumstance of the increasing prevalence ofa sort of periwin- 
“kle (tlisipan), sometimes in such masses that they practically cover the 
“bottom. These shell-fish destroy the little water-plants and fungi growing on 
“the bottom, on which the fish must feed, or they hamper their growth”. 
In conclusion VAN KAMPEN (?°) says concerning the marine fish-ponds 
in the environs of Batavia: “The fry feed, according to what the rearers say, 
“on the so called “tay-ayer”. This is the same thing as what is called 
“klekap” in Javanese, namely a soiled-gray mass consisting of a blue-green 
“alga (Oscillaria sp.). When the little fish have grown to be about 3 to 
“4 cM. long, they are given every day “lumut” (green algae, Vaucheria 
“sp. and others) chopped fine. Also the older bandeng are fed with algae 
“brought purposely into the ponds”. 
With the exception of this last quotation from VAN KAMPEN (2), the 
above quoted passages written by non-biologists, give us little solid infor- 
mation to go by. Moreover VAN KAMPEN’s (2) statement alone refers to the 
Batavia empangs, This in fact tallies perfectly with the data collected by 
myself. Only where VAN KAMPEN (#5) says that the older bandeng is fed 
with algae put purposely into the ponds, he mentions an excep- 
tional case; the algae on which the older bandeng feeds have mostly de- 
veloped on the spot. 
Besides “lumut”, i.e. green algae, recognizable as such with the naked 
eye, such as Chaetomorpha, Vaucheria, Spirogyra and Enteromorpha, VAN 
SPALL (*) mentions also as a by no means unimportant food for the bandeng, 
the droppings of sea-birds, and principally ofthe kuntul') andthe blekok'), 
i.e. Of herons. At Batavia I have never seen or heard’ anything about the 
bandeng eating the excrements of birds. The only remark I can make 
on this point is, that in October 1920 during a visit of a few hours 
among the tambaks near Bangil, | was struck with the numbers of the 
cormorants *) and herons which had made this pond-district their haunt. 
On my frequent excursions through the Batavia empang-district | never 
saw anything like it. 
') cf. notes !) and 2) page 219. 
2) According to Mr. M. E. G. BARTELS Phalacrocorax javanicus HORSF.. 
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