Thesis (M.Arch.)--University of Hong Kong, 1995. / Leaves 8 & 11 missing. Includes bibliographical references. Also available in print.

Thesis (MScAgric)--University of Stellenbosch, 2006 / Bibliography. Also available via the Internet.

The aim of this work was to investigate the nutrition of a popular ornamental fish, the swordtail (Xiphophorus helleri), under intensive aquaculture conditions. The study focused on the formulation and manufacture of artificial dry diets, as well as the influence of livefeed supplementation on growth and nutritional indices of both juvenile and broodstock fish. A combination of 65% fishmeal and 35% soya oil cake meal was found to closely approximate the essential amino acid profile of X helleri (r² = 94,3%) and lysine was identified as the first limiting amino acid. The influence of dietary protein and energy on the growth of X helleri was investigated by means of a growth trial comparing a range of nine test diets combining 3 crude protein (45,38 and 30%) and 3 digestible energy (16,5, 14,5 and 12,5 kJ/gram) levels. A high crude protein content (45% dry matter) and a protein to energy ratio of ≥ 27 mg protein per kJ digestible energy was shown to promote optimal growth rate and feed conversion ratio in juvenile X helleri. The final body protein and lipid content of the fish were significantly correlated with the dietary protein to energy ratio. The nutritional value of identical dietary formulations prepared by drum-drying or cold extrusion techniques and presented either as flake or crumble particles was evaluated in a growth trial and through analysis of vitamin C levels in the diets. Up to 27% of vitamin C activity was destroyed during the drum-drying of flake diets, while 80% of the remaining vitamin C was lost through leaching within 10 minutes of immersion in water. A crumble-type diet was shown to be acceptable to X helleri, and yielded significantly better growth rate and feed conversion than the equivalent flake feed. Almost 19% of fish fed the flake diets developed vitamin C deficiency symptoms including scoliosis and lordosis, while this was completely prevented by feeding crumbles, indicating a significant restriction of leaching losses from this type of particle. The use of livefeed (Daphnia spp.) as a daily supplement to dry feeds was shown to result in a significant improvement in growth rate and survival of juvenile swordtail fish. Furthermore, the synergistic action of nutrients contained in the livefeed resulted in an improvement in the feed conversion efficiency of the artificial formulation. While mortalities of 13,4% and 15% were recorded in fish fed exclusively on flake feed or Daphnia, no mortality occurred in the group fed the supplemented diet. Furthermore, the incidence of vitamin C deficiency symptoms was prevented by daily supplementation with Daphnia. Fish fed exclusively on Daphnia exhibited significantly more intense pigmentation due to carotenoids contained in the livefeed. In broodstock fish maintained primarily on flake diets, growth rate, feed conversion ratio as well as reproductive performance, as measured by fecundity, were significantly improved by daily livefeed supplementation. Weekly supplementation showed no measurable advantage over flake feed only. A direct correlation was demonstrated between fecundity and size of female fish with a mean fecundity of 190 embryos per female in those fed a daily Daphnia supplement. This was significantly higher than the yield from the non-supplemented or weekly supplemented treatments (133 and 140 embryos per female respectively). Despite these differences, the number of young harvested during the experiment did not differ between treatments and this discrepancy was ascribed to parental cannibalism of newborn juveniles. This phenomenon constitutes a major potential bottleneck in production with estimates of up to seventy percent of young lost in some exp experimental tanks. In conclusion, the present study demonstrated that established aquaculture nutrition principles and techniques are applicable to the tropical ornamental fish species, X helleri. It was demonstrated that by using balanced crumble feed formulations, and regular livefeed supplementation, production yields under intensive conditions may be significantly improved. Suggestions for future work on poeciliid production in South Africa include investigation of the economic implications of the recommendations stemming from this project, and further research into effective restriction of parental cannibalism of newborn fish.

In order to develop a system that could provide fish farmers with information to monitor stock performance and plan for a timely production, a computerised recording system was designed and tested on a trout hatchery in Scotland. It facilitated routine data capture on site with a small hand-held computer, programmed in BASIC language, which subsequently downloaded the data to a central desk-top microcomputer for further processing. Both direct and long-distance transmission via the telephone network using modems were possible. The LOTUS 1-2-3 general purpose software package, running on the microcomputer, was customised using 'macro' commands to accept the transmitted data and create files for storage on 'floppy' or 'hard' magnetic disks. Further information could be calculated and graphs and summary reports for stock control could be generated at will. Other customised LOTUS worksheets were developed to allow identification and access of specific historical data in order to calibrate regression equations and provide growth predictions for particular fish types. This information combined with cost and pricing details was further utilised by a linear programming package. Guidelines on optimum policies were formulated and sensitivity analyses could be performed. This production information system was implemented on the IBM-PC and the OLIVETTI M24 desk-top microcomputers and as field devices the SHARP PC 1500A and the HUSKY HUNTER were used. Since existing technology and 'off-the-shelf' software were utilised, the developed information system can be easily adjusted to suit the individual needs of different fish farms. However, the most important requirement for successful implementation would be the commitment and enthusiasm of the fish farm manager.

Thesis (M. Sc.)--University of Hong Kong, 2000. / Includes bibliographical references (leaves 73-80).

Typescript. / Digitized by Kansas State University Libraries

No description available.

published_or_final_version / Zoology / Master / Master of Science

Insecticides are widely used in SE Asian countries to control insect pests in rice, mainly stemborers (Chilo suppresallis) and brown plant hoppers (Nilaparvata lugens). The use of highly toxic insecticide compounds, however, is known to cause serious problem for fish culture in wet rice fields in many of these countries, particularly in Indonesia where this practice assumes a tremendous "house hold economic" importance, as well as being an essential part of the nation's inland aqua-culture production system. The laboratory and field experiments described were carried out to establish whether the application of five selected rice insecticides (fenobucarb, isoprocarb, buprofezin, diazinon and alphamethrin) would influence the growth and production of common carp fingerlings (Cyprinus carpio LINN.) raised in wet rice fields. Laboratory static toxicity tests revealed that the carbamate insecticides (fenobucarb and isoprocarb) were the least toxic insecticide compounds. The 96 hour Median Lethal Concentration (i.e the concentration that killed 50% of the test fish in 96 hours exposure period, under specified conditions) of these insecticides were 5.8mgl-1 and 5.3mgl-1, respectively. The synthetic pyrethroid insecticide alphamethrin was the most toxic insecticide with 96h-LC50 of 0.037mg1-1, while the organophosphate diazinon and the thiadiazin buprofezin showed intermediate toxicity to common carp (96h-LC50 = 2.3mgl-1 and 1.5mgl-1, respectively). A series of five field experiments were consecutively conducted, using 24 specially constructed rice field plots to accomodate the culture of common carp fingerlings for a period of 21 days. A single application of three dose regime, i.e 1/2X, 1 X and 2X of the recommended dose rate for insect control was given as treatment in each experiment. The survival of fish in all experiments were not significantly influenced by the insecticide treatment (P > 0.05). The growth rate and the production of fish biomass in rice fields treated with isoprocarb, buprofezin, diazinon and alphamethrin, were also found to be comparable with those in the untreated control plot (P > 0.05). In the rice fields treated with the highest dose rate of fenobucarb (1500gha-1 ,Al), the growth and production of fish were significantly lower than those in the untreated control rice fields (P < 0.05). Observations on the rice field biota revealed no definite pattern in the temporal changes of the population of zooplankton and macroinvertebrates both in the insecticide treated plots as well as in the untreated control plots. The minimum effects of the insecticide treatment to fish and rice field biota observed in the experiment were presumably due to several factors, mainly because a significant amount of the compounds were adsorbs by the rice field soil and aquatic vegetations and not onto the water, causing less toxicity, followed by the rapid flushing of the chemicals from the rice field system. The composition of the diet of common carp fingerlings in the rice field was found to be similar with those reported in the natural ponds, consisting mainly of aquatic insects (and their larvae), crustaceans, benthic macroinvertebrates and plant detritus. Based on the results of the present experiments, of the five insecticide compounds tested, diazinon and fenobucarb appeared to produce greater risk to fish when used in rice-fish farming. The use of agrochemicals in rice-fish farming should be carefully managed and controlled, using selected low toxic and non-persistent insecticides based on the result of laboratory and field toxicity tests.

Thesis (M.S.)--West Virginia University, 2002. / Title from document title page. Document formatted into pages; contains viii, 84 p. : ill. (some col.), col. map. Includes abstract. Includes bibliographical references (p. 65-69).