Efficiency of some cyanophytes as larval feed for silver carp (Hypophthalmichthys molitrix) and the culture of Spirulina platensis

Abstract

Six-day old carp (Hypophthalmichthys molitix) fry (mean weight 3 mg) were stocked at 5/l in aquaria. These were fed with unialgal cultures of three species of blue-green algae, namely: Anabaena sp., Oscillatoria quadripunctulata and Spirulina platensis. Best increase in weight was obtained when feeding consisted of Spirulina followed by those fed with Oscillatoria. Poor results were obtained when fry were fed solely with Anabaena. Weight gain was highest during the first two weeks with Spirulina as feed. On the other hand, survival of fry was higher (68%) with Oscillatoria than with Spirulina (54%). Proximate analysis of fish and algae were conducted. Spirulina seemed to be the most promising live food organism for larval rearing of silver carp. Thus, laboratory culture of the cyanophyte at different pH (9, 10 and 11) and two types of media (hog manure and urea) were investigated. Algal biomass production in a semi-continuous, outdoor tank system was also determined.