Acceptability
of raw Spirulina platensis by larval tilapia Oreochromis niloticus
J. Lu, G. Yoshizaki, K. Sakai, T. Takeuchi-2002
Fisheries Science, 68(1): 51-58
(from Current Contents)
Abstract:
Thirteen-day-old tilapia larvae (mean weight: 0.01
g), at the onset of exogenous feeding, were stocked at five fish per liter
in rearing tanks. They were fed unialgal cultures of Spirulina platensis
from varying ages [0, 12, 17, 21, and 28 days after the onset of exogenous
feeding with a standard length (SL) of 0.8cm, 1.8cm, 2.0cm, 2.5cm, and
3.0cm, respectively]. Feeding experiments on larvae fed different amounts of
raw Spirulina were also designed. Acceptability tended to improve with an
increase in the initial SL of the experimental larvae, and larval tilapia
from 2.0cm SL showed significantly rapid growth when fed raw Spirulina.
Larval tilapia that were fed solely raw Spirulina at a feeding rate of 30%
(on a dry basis) of bodyweight in the first 3 weeks, 10% in weeks 4-6, and
3% in weeks 7-10, kept growing without any abnormality. Final weight and SL
reached 3.2 +/- 0.4 g and 4.5 +/- 0.2cm (n=20), respectively, demonstrating
that raw Spirulina was accepted by tilapia even just after the onset of
exogenous feeding. Growth and survival rate of larvae fed Spirulina at
different feeding rates in the first 3 weeks just after the onset of
exogenous feeding showed a significant difference. Larval tilapia fed to
satiation had the best growth performance throughout the 10-week rearing
period, whereas those fed at a feeding rate of 10% stopped growing
eventually and stunting was found. The availability of an abundant supply of
Spirulina during the early stages seemed to be important for the normal
growth and development of tilapia. Raw Spirulina appears to be an effective
uni-feed for larval tilapia when developing a food chain of
phytoplankton-fish for a closed ecological recirculating aquaculture system
(CERAS).
(Tokyo Univ Fisheries, Fac Fisheries, Tokyo 1088477,
Japan, e-mail of T. Takeuchi: take@tokyo-u-fish.ac.jp)