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

Overall results of the study indicate that the availability of high concentrations of phyloplankton in the rearing medium favoured growth of T. nilotica fry to fingerling

Supplemental feeding of Tilapia mossambica

T. mossambica were grown to marketable size in floating cages in Laguna de Bay at a stocking density of 75/m2. Those given supplemental feed 1 (rice bran:ipil-ipil:fish meal, 60:20:20) showed significantly faster growth than those fed with supplemental feed 2 (chopped snails:rice bran, 30:70). Controls, without supplemental feeding, showed slower growth rates as compared to the supplement-fed lots. A more efficient feed conversion ratio was obtained for feed 1 (4:1) as compared to feed 2 (6:1). Laboratory experiments in aquaria showed the feasibility of improving the growth of tilapia with ipil-ipil (Leucaena leucocephala) leaf meal alone. Varying levels of ipil-ipil, given at 3, 6, and 9% of the body weight, increased the body weight to 0.75 g, 1.68 g, and 2.94 g, respectively. Moreover, the crude protein content of tilapia increased proportionately with increasing levels of ipil-ipil leaf meal. The significance of the above results in the light of establishing a tilapia lake farming industry and its effect on the improved nutrition of the people were discussed

Ipil-ipil leaf meal as supplemental feed for T. nilotica in cages

Tilapia nolotica fingerlings were grown to marketable size in cages in Laguna Lake at a stocking density of 150/m super(2). Those given supplemental feed of ipil-ipil leaf meal at varying levels showed faster growth compared to the control given rice bran alone. Experiments in aquaria showed that T. nilotica) can tolerate high concentrations of ipil-ipil leaf meal in feeds without showing any symptom of toxicity. Costs and returns analysis was done

Cannibalism among different sizes of tilapia (Oreochromis niloticus) fry/fingerlings and the effect of natural food

Experiments were conducted in jars, tanks and aquaria to determine the occurrence of cannibalism among 7 different size groups of Nile tilapia (Oreochromis niloticus ) fry and fingerlings. Cannibalism became more intense as the size difference increased. Big fry were less susceptible to cannabalism than small fry. On the other hand, bigger fingerlings were highly cannabalistic compared with smaller ones. This was evident as early as the first 10 minutes after stocking when fingerlings which usually stayed at the bottom moved swiftly towards the surface and swallowed the smaller fry. Availability of additional natural food in the growing medium affected survival of fry (mean weight = 9.3 mg) which were stocked with fingerlings (mean weight = 163.5 mg) in aquaria. Feeding with Spirulina proved more effective in reducing cannibalism than feeding with Navicula . After 5 days of rearing, fry survival was highest when fed with Spirulina (83.1%) followed by Navicula (16.6%) and the unfed control (5.6%)

The storage effect: definition and tests in two plant communities

Over 50 years ago, Hutchinson (1941) noted that variation in environmental conditions could alter the outcome of competition. One implication of his observation was that environmental fluctuations could promote coexistence, allowing many species to persist in a habitat where all but one would be excluded under constant conditions. By the end of the 1980s, Chesson and colleagues had clearly described the theoretical requirements for coexistence via the storage effect (Chesson and Warner 1981, Warner and Chesson 1985, Chesson and Huntly 1989). Yet despite the long history of these ideas, relatively few direct empirical tests of the storage effect exist. Studies from a variety of natural ecosystems provide partial evidence for the storage effect (Pake and Venable 1995, 1996, Kelly and Bowler 2002, Descamps-Julien and Gonzalez 2005, Facelli et al. 2005, Kelly et al. 2008), but tests of all the required conditions or quantification of the strength of the effect are much rarer (Cáceres 1997, Adler et al. 2006, 2009, Angert et al. 2009). The lack of rigorous case studies limits our ability to generalise about the role of the temporal storage effect in maintaining diversity. We know that multiple coexistence mechanisms will operate in different communities, but currently we cannot say where the storage effect makes an especially important contribution. This information will be essential for understanding the consequences of expected increases in climate variability (Karl and Trenberth 2003, Jain et al. 2005, Salinger 2005, Allan and Soden 2008), which could impact species diversity in systems where the storage effect is important (Adler and Drake 2008). Understanding the influence of the storage effect on coexistence across a variety of ecosystems is therefore a prerequisite for anticipating future changes in species diversity