217
production, may highly decrease during this period (Nabhitahata 1978) if training
is not successful. The period from 30 to 50 days, or 20 to 30 mm mantle length, is
appropriate for training. The older and larger they are, the more easily they can be
trained to accept dead food and a varied diet. Anil et al. (2005) began training cuttlefish to accept whole mysids, Acetes sp., and fish after 50 days, while Minton et al.
(2001) began with thawed shrimps, Penaeus sp., after 70 days. Overall, the success
of training depends on the right timing as well as the experience of human trainers.
Trained cuttlefish are fed ad libitum, twice daily.
Late training for accepting dead food at an older age, from 30 to 70 days, is considered to affect the subsequent higher growth and final size (Minton et al. 2001).
The advantage is the larger size of the cuttlefish at training, but the extension of the
nursing phase to 40 days with additional costs regarding live food should also be a
concern in large-scale cultures.
Preliminary attempts to train S� pharaonis to feed on artificial diets instead of
fish meat did not succeed (Sangpradab et al. 1984), and no further studies have been
reported.
Consequent changes in feeding behaviour can be seen. Feeding behaviour
changes from using tentacles to using only arms for the seizing of food, without the
positioning step (Messenger 1977) when they are fed on dead feed. The feeding behaviour of one cuttlefish also visually stimulates others in the same tank to behave
similarly, as also observed in S� officinalis (DeRusha et al. 1989). Such stimulation
accelerates the acceptance of dead food and reduces the time required for training.
12.6.3 Growth
Growth can be observed from changes in colour patterns and morphology. After
about 60 days of age, the normal colour pattern of the cuttlefish turns to dark brown
with scattered small black rings on the dorsum and a dark brown colour on both
fins. The fin length is about 95 % of the mantle. After about 90 days of age, sexual
dimorphism may be recognised by the colour pattern (Nabhitabhata 1978). The
male displays brown-white transverse stripes or a tiger pattern on the dorsum. The
female colour pattern does not obviously change with growth. The tiger pattern of
the male gradually turns clearer with growth to 120 days of age.
The daily growth rates in weight increase with age and then decrease corresponding to the period of sexual maturity and mating. In an open system, the daily
growth rates in terms of weight were 7.2 % at 60 days after hatching and these
increase to 7.9 % at 70 days after hatching and decrease to 6.2 and 4.5 % after mating at about 90 days after hatching and spawning at about 110 days after hatching,
respectively (Nabhitabhata and Nilaphat 1999). The first spawning is observed at
a mantle length of about 70 mm (50 g) and generally to about 100 mm (100 g). On
and after a 10-day period, the daily growth tends to decrease with the increase in
age. For the overall life cycle of 210 days, the average daily growth rate is 1.4 % in
mantle length and 3.4 % in body weight at 28 °C.
12 Sepia pharaonis
production, may highly decrease during this period (Nabhitahata 1978) if training
is not successful. The period from 30 to 50 days, or 20 to 30 mm mantle length, is
appropriate for training. The older and larger they are, the more easily they can be
trained to accept dead food and a varied diet. Anil et al. (2005) began training cuttlefish to accept whole mysids, Acetes sp., and fish after 50 days, while Minton et al.
(2001) began with thawed shrimps, Penaeus sp., after 70 days. Overall, the success
of training depends on the right timing as well as the experience of human trainers.
Trained cuttlefish are fed ad libitum, twice daily.
Late training for accepting dead food at an older age, from 30 to 70 days, is considered to affect the subsequent higher growth and final size (Minton et al. 2001).
The advantage is the larger size of the cuttlefish at training, but the extension of the
nursing phase to 40 days with additional costs regarding live food should also be a
concern in large-scale cultures.
Preliminary attempts to train S� pharaonis to feed on artificial diets instead of
fish meat did not succeed (Sangpradab et al. 1984), and no further studies have been
reported.
Consequent changes in feeding behaviour can be seen. Feeding behaviour
changes from using tentacles to using only arms for the seizing of food, without the
positioning step (Messenger 1977) when they are fed on dead feed. The feeding behaviour of one cuttlefish also visually stimulates others in the same tank to behave
similarly, as also observed in S� officinalis (DeRusha et al. 1989). Such stimulation
accelerates the acceptance of dead food and reduces the time required for training.
12.6.3 Growth
Growth can be observed from changes in colour patterns and morphology. After
about 60 days of age, the normal colour pattern of the cuttlefish turns to dark brown
with scattered small black rings on the dorsum and a dark brown colour on both
fins. The fin length is about 95 % of the mantle. After about 90 days of age, sexual
dimorphism may be recognised by the colour pattern (Nabhitabhata 1978). The
male displays brown-white transverse stripes or a tiger pattern on the dorsum. The
female colour pattern does not obviously change with growth. The tiger pattern of
the male gradually turns clearer with growth to 120 days of age.
The daily growth rates in weight increase with age and then decrease corresponding to the period of sexual maturity and mating. In an open system, the daily
growth rates in terms of weight were 7.2 % at 60 days after hatching and these
increase to 7.9 % at 70 days after hatching and decrease to 6.2 and 4.5 % after mating at about 90 days after hatching and spawning at about 110 days after hatching,
respectively (Nabhitabhata and Nilaphat 1999). The first spawning is observed at
a mantle length of about 70 mm (50 g) and generally to about 100 mm (100 g). On
and after a 10-day period, the daily growth tends to decrease with the increase in
age. For the overall life cycle of 210 days, the average daily growth rate is 1.4 % in
mantle length and 3.4 % in body weight at 28 °C.
12 Sepia pharaonis