ENHANCEMENT OF STRESS RESISTANCE OF THE GUPPY
POECILIA RETICULATA THROUGH FEEDING WITH VITAMIN C SUPPLEMENT
L.C.
Lim, P. Dhert, W.Y. Chew, V. Dermaux, H. Nelis, P. Sorgeloos-2002
Journal of the World Aquaculture Society, 33(1):
32-40
Abstract:
This study investigated the use of vitamin C
supplement in formulated diets and live Artemia juveniles to enhance the
stress resistance of the guppy Poecilia reticulata. To evaluated the stress
resistance, fish were subjected to osmotic shock in pre-aerated water
containing 35 ppt sodium chloride. Ascorbyl acid-polyphosphate and ascorbyl
palmitate were used as vitamin C sources for formulated diets and live
Artemia juveniles, respectively. Results showed that guppies fed moist
formulated diets supplemented with ascorbic acid at 1,000 mg/kg or 2,000
mg/kg diet displayed significantly higher levels of stress resistance than
fish fed control formulated diet for 13 d. The stress resistance of fish fed
a lower dose (200 mg/kg diet), however, did not differ significantly from
that of the control. On the other hand, the stress resistance of guppies fed
Artemia juveniles bio-encapsulated with 10% or 20% acorbyl palmitate did not
show significant difference from that of fish fed control Artemia after 20
d. The stress resistance of these three groups of Artemia-fed fish, however,
was significantly higher than that of fish fed the control formulated diet.
Biochemical analyses showed that raising the ascorbic acid level in feeds
resulted in a concomitant increase in the incorporated ascorbic acid level
in the whole-body tissue of the guppy. The increased stress resistance of
the guppy fed a vitamin C supplemented diet has also been demonstrated in
four commercial farms. The potential application of the improved stress
resistance in the ornamental fish industry was discussed.
(Freshwater Fisheries Centre, Agri-food &
Veterinary Authority of Singapore, Sembawang Research Station, Lorong
Chencharu, Singapore 769194, Republic of Singapore, e-mail of P. Sorgeloos: Patrick.Sorgeloos@rug.ac.be)