The effects of 3 temperature treatments on activity, feeding, growth, development and survival of young milkfish (Chanos chanos) were investigated under laboratory conditions. It is believed that the results may be applied to develop a land-based mass production technology in rearing milkfish fry to fingerlings

Unggui, A.

Villaluz, A.C.

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Effects of temperature on behavior,  growth,
development and survival of young milkfish, Chanos
chanos Forsskal 
Villaluz, A. C. & Unggui, A. 
Date published: 1981 
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To cite this document :  Villaluz, A. C., & Unggui, A. (1981). Effects of temperature on behavior,
growth, development and survival of young milkfish, Chanos chanos Forsskal. SEAFDEC
Aquaculture Department Quarterly Research Report, 5(3), 1–4.
Keywords :  Controlled conditions, Fish culture, Rearing, Temperature effects, Chanos chanos
To link to this document :  http://hdl.handle.net/10862/2390
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Effects of temperature on behavior, growth, development and 
survival of young milkfish, Chanos chanos Forsskal
A .C . V illa lu z  and A . Unggui
Effects of three temperature treatments on activity, feeding, growth, development and 
survival of young milkfish (Chanos chanos) were investigated in the laboratory. Depressed tempe­
rature ( <  22.6°C), like hypoxial condition ( <  1 ppm O2) and nightfall, decreased activity, 
responsiveness and food intake, while elevated temperature of up to 33°C had the opposite 
effects. Growth and development were fastest in fish maintained in high test temperature 
(x̄ = 29.55°C) and followed by specimens in ambient temperature treatment (x̄ = 26.79°C). 
Those in low test temperature (x̄ = 20.67°) had the least growth and completely inhibited to 
metamorphose into juveniles during the 3 month rearing period. Growth response of fish trans­
ferred to another test temperature depended not only on present rearing temperature but also 
on previous acclimation temperature. Highest survival (x̄ = 99.7%) was obtained in high tempera­
ture treatment but not significantly different (P >  0.05) from ambient temperature (x̄ = 97.7%). 
However, survival in both higher test temperatures differed (P <  0.05) from low temperature 
treatment (x̄ = 76.7%) (Figure 1).
The milkfish in their natural habitat or pond environment encounter daily or seasonal 
temperature variations which greatly influence their growth and well being. Lin (1968) reported 
that milkfish in Taiwan behave normally at temperatures between 20° to 33°C and become 
sluggish below 20°C. The young milkfish in the present study, however, were still sluggish at 
temperatures of up to 22.6°C. This discrepancy may be due to lower thermal experience of 
Taiwan specimens which provide them anticipatory adjustment to cope with lower temperatures.
Field observations also indicate that young milkfish abandon schooling behavior at night 
with decreased activity and responsiveness to movements and vibrations in their environment 
(Buri 1980). Since predation is the most probable cause of mortalities in nature and in ponds, 
lowering of activity and of ability to respond to stimuli whether it be brought about by nightfall 
or environmental stressors such as depressed temperature or hypoxial condition, would render 
the fish vulnerable to intense predation.
Milkfish swimming against the current when pond water is being renewed has been regarded 
by Schuster (1960) as a rheotactic response. According to Villaluz (1953) such habit is not. 
observed in well oxygenated and deep ponds which are cooler than shallow ponds. A parallel 
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Figure 1. Survival curves of young milkfish at various temperature treatments. There were three 
replicate groups at each treatment. Survival rate in high temperature not significantly 
different at P < 0.05 from ambient temperature but both treatments significantly 
different at P  <  0.05 from low temperature.
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situation has been observed in the present experiment when the fish crowd to source of aeration 
under hypoxial condition while generally ignoring the same when rearing water is newly replaced. 
This, coupled with increased activity of fish when transferred to higher or lower temperature 
than acclimation temperature, indicates active avoidance of environmental stressors and not a 
response to water current per se.
In the light of current observations, it is apparent that milkfish are opportunistic feeders 
capable of taking in a variety of food and taking them from several different situations. They 
feed by preference, in the present case, Brachionus, but turn to other food and even their own 
faeces when their preferred food has been exhausted.
Milkfish in higher temperatures have the fastest food intake. Since the rate of digestion is 
also highly temperature dependent and can be measured by time elapsing between food intake 
and defecation (Kapoor et al . 1975), the primary process of digestion in the milkfish therefore 
increased by a factor of about 2 times for a 10°C change. The effect on growth is clearly illus­
trated by comparing the monthly means of length and weight of specimens maintained in low 
(x̄ = 20.67°C) and high (x̄ = 29.55°C) test temperatures. Except in the first month of rearing, 
mean linear measurements of fish held in high temperature are roughly 2 times greater than those 
maintained in low temperature and monthly mean weight about 10 times greater. Such effect was 
also noticed when milkfish were transferred to lower or higher test temperatures in the third 
month of rearing.
The approximate temperature limits for successful development from larval to juvenile 
periods appear to be 23.7 to 33°C. Rate of development is faster at high temperature and depen­
dent on length rather than age of fish. Since increasing fish biomass would enhance growth and 
development rate related to length of fish, interaction between temperature and fish biomass 
on development of young milkfish is expected although not demonstrated in the present study.
Results also show that daily exposure of early transition stage to increasing temperature 
at 1°C per hour would be lethal if the temperature is increased from 25.8 to 34°C. This means 
that the time of exposure is more critical to survival than the magnitude of the temperature 
change. However, a very high recovery potential from thermal stress is indicated since all the 
affected fish except one recovered completely, assuming normal activity and feeding within 
30 minutes of transfer to 27°-29°C.
Elevated temperature stimulates appetite and digestive efficiency in high temperature treat­
ment. The absence of this stimulating factor in ambient temperature and the depressive effect 
of low temperature on appetite may have resulted into poor food utilization. Burrows (1972) 
states that at higher temperature diet utilization efficiency is increased and when food intake is 
high, the vitamin content per unit weight of diet can be lower than when the intake is reduced. 
Based on this, it appears that "nutritional stress" may have caused mortalities in ambient and 
low temperatures. Moreover, the symptom of the disease strongly suggest vitamin deficiency 
considering that all dead fish in low temperatures were suffering from scoliosis and lordosis. 
These conditions are attributed by Halver (1972) as vitamin C deficiency. The detrimental effect 
of overcrowding, however, cannot be precluded. It can be pointed out that when stocking density 
was decreased no mortality occurred and the fish in all treatments were healthy at the end of the 
experiment.
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The methods and results of the current experiment can be applied to develop a land-based 
mass-production technology in rearing milkfish fry  to fingerlings and no insurmountable d ifficul­
ties are foreseen. The advantages of the new system would include the following:
Mortalities due to predation and unfavorable environment which are the primary causes 
of low survival in traditional nursery ponds can be eliminated;
Milkfish fry can be grown into fingerlings at high density of 10,000 pieces/m3. The area 
required to produce 1,000,000 fingerlings for example would be reduced to 200 m2 instead 
of 10,000 m2 or more as practiced presently;
Growth and size variation can be controlled through fish biomass and/or thermal 
manipulation;
Pre-conditioning of fish to salinities obtained in ponds or other bodies of water where the 
fish would be stocked can be facilitated. This would prevent stress and minimize mortalities 
after stocking. High mortality of about 36% has been reported to occur within 3 days of stock­
ing milkfish fingerlings in Laguna de Bay (Smith, 1981); and,
Fish can be held indefinitely w ithout impairing their well being and possibly improve their 
growth potential.
Literature cited:
Buri, P. 1980. Ecology of the feeding of milkfish fry and juveniles, Chanos chanos (Forsskal) 
in the Philippines, Mem. Kagoshima Univ. Res. Center S. Pac. 1(1): 25-42.
Burrows, R.E. 1972. Salmoid husbandry techniques p. 375-402. In J.E. Halver (ed.) Fish Nut­
rition. Academic Press, New York, San Francisco and London.
Halver, J.E. 1972. The vitamins p. 29-103. In J.E. Halver (ed.) Fish Nutrition. Academic Press, 
New York, San Francisco and London.
Kappor, B.G., H. Smit and T.A. Verigina. 1975. The alimentary canal and digestion in teleost, 
p. 109-239. In F.S. Russel and M. Young (eds.) Adv. Mar. Biol. Vol. 13. Academic Press, 
London and New York.
Lin, S.Y. 1968. Milkfish farming in Taiwan. Fish Culture Report No. 3. Fisheries Research 
Institute 63 pp.
Schuster, W. 1960. Synopsis of biological data on milkfish Chanos chanos Forsskal), 1975. 
FAO Fisheries Synop. No. 4 FAO, Rome, Italy.
Smith, T.R. 1981. The economics of the milkfish fry and fingerling industry of the Philippines. 
ICLARM Tech. Report No. 1, 147 pp.
Villaluz, D.K. 1953. Fish farming in the Philippines. Bookman, Inc., Manila, Philippines. 366 pp.
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Effects of temperature on behavior, growth, development and survival of young milkfish, Chanos chanos Forsskal

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Effects of temperature on behavior, growth, development and survival of young milkfish, Chanos chanos Forsskal

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