SUNIER: Marine fish-ponds of Batavia. 217 
Map Il), that at Batavia the frequently mentioned “algal”')-vegetation 
composed of Chaetomorpha etc. (cf. photos no. 2, 3, 4, 6,8, 9, 14 and 15; 
Plates VII, VIII, IX, XI, XIV, XV, XXII and XXIII) is allowed to develop 
again as food for the bandeng ?) before new fish is turned into a pond 
which has been cleared of bandeng. I must now add to this that imme- 
diately after the catching away of all the fish, and consequently before the water- 
vegetation is allowed to recover, the water is usually entirely renewed, and 
if possible the whole pond-bottom is laid dry for a couple of days. This 
replenishing with new water together with the laying dry of the bottom 
are effected with a view to the development of the aquatic vegetation in 
general, therefore of the tay-ayer organisms (Schizophyceae, Diatoms) as 
well as of the “algal” !)-vegetation°). 
Whereas in the vicinity of Batavia most of the Chinese pond-owners 
and also Mr. Görs, allow the “algal” '!) vegetation to develop as food for 
the bigger bandeng, this does not seem to be done in other parts of Java, 
where the marine ponds belong to the native population. Also the bigger 
bandeng is then obliged to feed on “tay-ayer” organisms. The development . 
of the “tay-ayer”-organisms is then more or less actively promoted by the 
more or less regular draining-dry of at least the central part of the pond, 
when the fish retire to the deeper belt-ditch. In this connection VAN 
KAMPEN’s (?°) remark is important: “The culture of bandeng (Chanos 
orientalis) has reached a high degree of development at Batavia”. Also 
TREUB (°°) says that “the bandeng-culture in salt-water fish-ponds in the 
neighbourhood of Batavia is on a fairly high level”. Personally I am only 
acquainted with the Batavia empangs situated between Kamal and Tjilintjing. 
During a very short visit to the tambaks of Pasuruan and Bangil I certainly 
did not receive the impression, to put it mildly, that these are worked better 
than Mr. Görs’s or the other Batavia sea fish-ponds which are Chinese- 
owned. It would accordingly appear to me that the method pursued by 
Mr. Görs and the Chinese empang-owners near Batavia (as also in a few other 
places by native tambak-proprietors) in which only the young bandeng 
are fed on “tay-ayer’, but the older fish on “algae”'), is an improvement 
on the native method which obliges the bandeng always to feed on 
“tay-ayer”’ organisms. 
Mr. Görs once told me that the rearing of bigger bandeng with “tay- 
ayer” and with “algae” ') are two different cultures, consequently produc- 
') cf. note page 209. 
2) In Chapter IV we saw that there are a number of indications tending to make 
it probable that a luxuriant development of the submerged vegetation is favoured by 
salinities either lower or but little higher than about 25°/. In this place I may be 
allowed to add that VAN SPALL (°) relates how bandeng-rearers of Besuki (p.36) and 
Probolingo (pag. 39) are of opinion that those are the best ponds which can be supplied 
not only with salt water but with fresh water as well; it seems however that VAN SPALL 
himself does not share this opinion. 
3) That a strong revival of the “algal”-vegetation also sets in after the ceasing - 
of the heavy west-monsoon showers, i.e. after a natural change in the fish-ponds as 
biological environment, I have already mentioned in Chapter IV. 
