Their density causes them to sink lower in brackish water until they eventually find bottom in the shallow bays and estuaries and in this way are gradually dispersed all long the coast. Then a metamorphosis takes place and the feeble Leptocephalus is transformed into the active little fish which swims vigorously against the current and feeds incessantly and voraciously all the time.
In a recent report on the Fisheries of the Straits Settlements and Federated Malay States the writer drew attention to the Chinese fish-traps called pompang and other licensed fixed engines known as ambai, langgai, etc., of which there are several thousand between Penang and Port Swettenham. Though there are many kinds of these traps they all work on the same principle. In every case there is a wide V-shaped entrance terminating in a long funnel-shaped bag made of sacking or plaited split bamboos. The position of these traps is arranged with respect to the currents and tides so as to intercept the larvae and immature fish during their denatant drift to the shallows. Most of these traps float, and swing round with each tide so as to take toll both with the ebb and the flow.
An examination of the contents of these traps shews that in addition to immature fish, which any Malay fisherman will tell you are the fry of valuable food fish, the bulk of the catches are made up of feeble, attenuated, small-headed larval-like fishes which the Malays call Bunga ayer and to which they attach no value.
There can be little doubt that scientific investigation will prove that the Bunga ayer are valuable food-fish in the Leptocephalus stage.
This subject has been treated at some length because of its great economic importance and because the questions raised cannot be answered except by a specialist in marine biology.
Though myriads of larval and immature fish are caught daily for duck food, pig food and manure, and thousands of pikuls are exported as dried fish refuse, it has been argued, while admitting ambai catches are used mainly as pig food, that it appears a debatable point whether the flesh value thus produced is not as reat as the extra fish value which might be caught if the fry killed by ambai were left undisturbed!
We cannot afford to allow such points to remain debatable.
Let us go on with the life history of the tiny fish which we left in the first stage of an active existence in the shallow waters near the coast. These shallows are the nurseries or recruiting grounds where the fry keep together in schools or shoals.
"After a period in relatively shallow water, the shoal migrates to deeper water. At first the migration is not to a great distance, but with growth the annual pulsation becomes greater and greater.
