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
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 0.8 cm, 1.8 cm, 2.0 cm,
2.5 cm, and 3.0 cm, 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 2.0 cm 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 ± 0.2 cm (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).
(Department of Aquatic Biosciences, Faculty of Fisheries, Tokyo University of Fisheries, Minato, Tokyo 108-8477, Japan, Tel/Fax: 81-3-5463-0545. Email of T. Takeuchi: take@tokyo-u-fish.ac.jp)