Algal production in wastewater: Progress and problems.

Algal production in wastewater is reviewed in two major areas: (1) production of single-cell proteins, and (2) its integration with aquaculture for the production of natural feeds. Progress achieved so far in the various aspects of algal production in the laboratory and outdoors are discussed, as are biotechnological problems in the operation and maintenance of high-rate algal ponds. The need for more basic and applied research is emphasized

Finfish nutrition in Asia: a review.

This review paper highlights counry reports presented at the Workshop on Asian Finfish Nutrition Sponsored by the International Development Research Center of Canada in 1983. Result of researches on the amino acid, lipid, mineral and vitamin requirements of some cultured finfishes in the larval, juvenile and broodstock stages are discussed. Complete essential amino acid requirements have been determined for common carp; only three have been qualified for tilapia. Many researches were conducted to replace trash fish and fish meal as protein source in fish diet. For O. niloticus, soybean meal can replace 50% of the fish meal in the grow-out diet. Essential fatty acids influence the dietary value of live food organisms for fish larvae. Rotifers cultured with yeast were low in W3 highly unsaturated fatty acids while those grown in Chlorella were high in 20: 5W3. Similarly, "lablab" showed higher W3/W6 ratio than "lumut". On the other hand, chemical, and Artemia from two sources showed that mineral is not the principal factor in the dietary value of natural feeds. Over-all, fundamental knowledge on the nutritional requirements of finfishes in the region is lacking

Algal production and utilization relevant to aquaculture in the Philippines

An outline is given of research conducted at the Aquaculture Department of SEAFDEC at Rizal, Philippines regarding algal culture and utilization. Culture methods for both brackishwater and freshwater algae are described and details given of applications of microalgae in the aquaculture industry, which include feed for fish and shrimp larvae

Acclimation of Penaeus monodon postlarvae to fresh water

Gradual acclimation of Penaeus monodon Fabricius to fresh water was conducted in glass aquaria and marine plywood tanks over a one-day, two-day, and three-day acclimation periods. Different stages of postlarvae were tested for their hardiness to acclimation. P35 postlarvae had a high percent survival of 98-99% while lower values were obtained for P20 and P90. A three-day acclimation period was favorable for all ages of postlarvae. Shorter durations of acclimation produced survival values as low as 20% This stress effect was apparent with P20 and P90 but not with P35 which showed high survival regardless of the length of acclimation

An assessment of algal growth in net cages in Laguna Lake

SEAFDEC Aquaculture Department No. 105.Quantitative determination of the algal population, in terms of cells/ml and biomass/ml, was conducted during the first month of growing P. monodon postlarvae in Laguna Lake. Algae were sampled from each side of net cages at depths of 15, 30 and 45 cm below the water surface. Accumulation of algae appeared to be influenced by the direction of water flow. Moreover, growth of algal species was inversely proportional to depth of water. After two weeks, algal biomass was estimated to reach 4.5 kg per cage (1 x 1 x 1 m). Diatoms (Chrysophyta) predominated throughout the experimental period followed by members of Cyanophyta and Chlorophyta

Fry-to-fingerling production of Tilapia nilotica in aquaria using phytoplankton as natural feed

Two experiments were conducted to demonstrate the efficiency of phytoplankton as natural feed in fry-to-fingerling production of Tilapia nilotica . In the first experiment, growth and survival rates of fry given a sustained supply of algae increased considerably over the control fed with rice bran. In the second experiment, T. nilotica were grown in "green" water with phytoplankton concentrations adjusted to the following densities (cells/ml): high, 150-175 x 10 super(3); moderate, 90-120 x 10 super(3); and low, 50-60 x 10 super(3). Increasing the algal densities in the rearing medium enhanced growth of fry. Highest weight increments were obtained with high and moderate phytoplankton concentrations

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

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

Acceptability of five species of freshwater algae to tilapia (Oreochromis niloticus) fry

Unialgal cultures of Oscillatoria quadripunctulata, Chroococcus dispersus, Navicula notha, Euglena elongata, and Chlorella ellipsoidea were fed to tilapia fry for 30 days. Mean weights and survival rates of the fry were highest when given Navicula (105.6 mg, 86%) and Chroococcus (89.1 mg, 90%). Oscillatoria, a filamentous cyanophyte, showed limited acceptability to tilapia fry, possibly because of its larger size in comparison with Chroococcus. Fry fed Chlorella and Euglena did not survive at all. C14-labeled algae of the above species were fed to tilapia fry of varying ages. Assimilation rates per fry after 24 hours of feeding with a suitable algal species increased with the age of the fry. Moreover, the same trend as in the growth and survival experiments was observed, i.e., the highest assimilation rates were obtained in 40-day old tilapia fry given Navicula and Chroococcus as natural feeds. On the other hand, negligible amounts of the other three algal species tested were assimilated by tilapia fry. The above results were explained in terms of the enzyme secretion of tilapias. There seemed to be no transition stage in the feeding habit of both fry and adult tilapia. The acceptability of plant matter in the diet of even the early larval stages was demonstrated