108 Fish as feed inputs for aquaculture – Practices, sustainability and implications
from 4 to 5. In crab farming and fattening, the use of compounded feeds is relatively
insignificant. Another of the more recent developments is the production of gravid
females for niche markets, such as in Chanthaburi province, Thailand (see Box 9).5.4.2 Lobster fattening
Lobster fattening is a relatively recent activity that is most intensely practiced in Viet
Nam (Phan, 2007). Two species of spiny lobster are fattened in Viet Nam, Panulirus
ornatus and P. homarus, which are now almost always reared in floating net cages as
opposed to net pens, as in the past. It is estimated that the current annual fattened lobster
production in Viet Nam is 1 000 tonnes (www.spc.int/aquaculture/site/commodities/
rock_lobster.asp?ou=pdt&pdt=rock_lobster&comm_name=Rock%20Lobster).
In lobster fattening, the food source used includes trash fish/low-value fish, as
well as molluscs such as blood cockle (Andara spp.), small crabs (Calappa spp.) and
swimming crabs (Portunus spp.) (Box 10). In general, the quality of the trash fish/
low-value fish fed to lobster is relatively high, with prices ranging from VND10 000
to 13 000 per kg, and often accounting for between 60 to 70 percent of all recurrent
costs. However, the farmgate price for fattened lobster is one of the highest among
cultured species, averaging VND312 000 and 627 000/kg for P. homarus and P. ornatus,
respectively, of average weights ranging from 0.2 to 0.4, and 0.8 to 1.6 kg. In view of the
“mixed” nature of the aquatic feeds used in lobster fattening and also because the total
production is relatively small, no attempt was made to estimate the volume of trash
fish/low-value fish used in this practice.5.5 Use of trash fish/low-value fish in mollusc culture
The majority of molluscs cultured are filter feeders, in particular, bivalves. Among
other molluscs, feeding is associated with the culture of the high-valued abalone species
(Haliotis spp.). However, in certain Asian countries, the culture of the gastropod
commonly known as the spotted Babylon has developed rapidly, particularly in
Thailand, Viet Nam and China (Box 11). Sixteen species of Babylon are known from
Indo-Pacific waters. However, the
most commonly cultured species
is Babylonia areolata, which
is reared only in Thailand, Viet
Nam and China. Little published
information is available on culture
methods, growth rates, production
and other related parameters
(Chaitnawisuti, Kritsanpuntu and
Natsukari, 2005; Kritsanpuntu et
al., 2005). The total production of
Babylon in Asia is unknown, but is
currently conservatively estimated
to be 70 tonnes. Babylon is sold
live to the restaurant trade, China
being the main market.
Babylon is fed trash fish/low-
value fish throughout its grow-
out phase, which lasts from three
to five months depending on the
market of destination. In Thailand,
the grow-out period is generally
longer and the harvesting size
ranges from 50 to 60 g/individualBOX 11
Babylon snail culture
The growth of Babylon snail culture in the region, which
commenced about six to eight years ago, has resulted in
a marked decline in farmgate/export price. For example,
a kg of Babylon produced in Thailand that was exported
at THB500–580/kg (US$1=THB40) consisted of 15 to 20
individual animals that were sold live. However, increased
Chinese production over the last three years, along with
increased production and export from Viet Nam to China,
has caused the overall
farmgate price to decline
markedly. The farmgate
price of live Babylon
exported to China from
Thailand has decreased
from THB200–250 kg in
late 2005 to THB150–180/
kg in December 2006, making the culture practice almost
economically unviable, especially within the context of
increasing prices for trash fish/low-value fish.Photo: Babylonia areolata