Acceptability of five species of freshwater algae to tilapia (Oreochromis niloticus) fry
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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.
Pantastico, J. B., Baldia, J. P., & Reyes Jr., D. (1985). Acceptability of five species of freshwater algae to tilapia (Oreochromis niloticus) fry. In C. Y. Cho, C. B. Cowey, & T. Watanabe (Eds.), Finfish Nutrition in Asia : Methodological Approaches to Research and Development (pp. 136-144). Ottawa, Canada: International Development Research Centre.
PublisherInternational Development Research Centre
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An investigation of enzyme and other protein polymorphisms in Japanese stocks of the tilapias Oreochromis niloticus and Tilapia zillii Samples of Oreochromis niloticus and Tilapia zillii were collected from the hatcheries of Osaka Prefecture Fisheries Experimental Station and Shiga Prefecture Fisheries Experimental Station, Japan, respectively. The samples were used for screening polymorphisms in 13 enzymes, skeletal muscle proteins and hemoglobins by horizontal starch gel electrophoresis. Among 35 loci examined, 12 loci for the 10 enzymes, sarcoplasmic protein and hemoglobins were polymorphic in O. niloticus and 2 loci for 2 enzymes were polymorphic in T. zillii. The observed numbers of phenotypes for respective loci agreed well with Hardy-Weinberg expectations. The genetic basis for each polymorphism is discussed. This investigation provides basis information on the status of these tilapias in Japan.
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Aquaculture, 2004 - ElsevierDisease due to luminous Vibrio has been a major problem of the shrimp industry. Different technologies have been introduced to control the disease. One of the techniques reported to work against luminous bacteria in the Philippines is the green water culture system (or finfish–shrimp integrated culture system). A green water culture system is an innovative technique wherein shrimp are cultured in water collected from a pond where tilapia or other fish species are grown. In some cases, the fish are cultured in an isolated net pen inside the shrimp culture pond. This study clarifies the effect of one component of the green water culture system, the presence of all male tilapia (Tilapia hornorum) on luminous bacteria Vibrio harveyi. Results showed that stocking tilapia at a biomass not lower than 300 g/m3 efficiently inhibited the growth of luminous bacteria in shrimp (biomass=80 g/m3) rearing water without the growth of microalgae.
Effect of shrimp biomass and feeding on the anti-Vibrio harveyi activity of Tilapia sp. in a simulated shrimp–tilapia polyculture system The efficiency of Tilapia hornorum to control luminous bacteria in a simulated shrimp farm environment has been reported. However, the effects of different factors such as feed input and the shrimp biomass were not taken into consideration. This study investigated the effect of feeding and increased shrimp biomass on the efficiency of tilapia to inhibit the growth of luminous bacteria. Results showed that feeding enhances the antibacterial activity or improves the efficiency of tilapia to inhibit the growth of luminous bacteria. However, the efficiency of tilapia at a biomass of 500 g/m3 is reduced if the shrimp biomass is greater than 80 g/m3. This explains the discrepancies in the results obtained in the use of tilapia to control luminous bacterial disease in shrimp ponds. The effect of starvation on the bacterial load of tilapia, grouper and milkfish feces and the amount of feces in the intestine was also investigated. Results showed that total bacterial and presumptive Vibrio count of fish feces decreased after 1 week of starvation except for the presumptive Vibrio count of grouper. The amount of feces in the intestine also decreased as starvation progressed. Moreover, bacteria isolated from the three species have antibacterial activity against the luminous bacteria Vibrio harveyi.