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Influence of insect´s components in fish feed on production, health and quality of fish.
HLÁVKOVÁ, Markéta
The first part of my work is devoted to review of alternative components in feeds for fish with special focus on insect. The second part of my work is based on the feeding experiment. Rainbow trouts (Oncorhynchus mykiss) were bred in the aquaria at the Faculty of Fisheries and Protection of Water JU in Vodňany. Experiment was performed in three replications, in 300 litre aquaria with 8 - 10 fish per aquarium. Fish were divided into 5 groups according to the type of feed used. Control group was fed the commercial granule feed and the other four groups were served insect in certain percentage. It was a cricket (Acheta domesticus) and the maggots of giant mealworm beetle (Zophobas morio).Weight and length of fish was registered three times during 2 months of experiment. The sensory analysis of fish meat was done for evaluation of aroma, taste, after taste and consistence of fish muscle. The results show that diet containing insect did not significantly influence weight and growth. In the contrast, sensory analysis proved the difference in analysed parameters. The feed containing only insect was identified as an inappropriate alternative feed. In conclusion, the insect can be used as the alternative feed for fish in the aquaculture. Nevertheless, it is recommended to combine the insect with commercial feeds.
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The effect of atenolol on a fish organism
BOŘÍK, Adam
Pharmaceuticals and their metabolites are emerging pollutants of aquatic environment associated with our modern society. The aim of this bachelor's thesis was to get information about potential hazard levels of atenolol occurring in surface waters and its effects on juveniles of rainbow trout (Oncorhynchus mikyss) as a model organism. The effect of environmentally relevnt concentrations of atenolol was assased in vivo by using biochemical markers. Activity of enzymatic reactions EROD (CYP 1A), MROD (CYP 1A2) and PROD (CYP 2B) were tested as possible biomarkers. The experimental work aimed to verify wheter selected cytochromes P450 are suitable to evaluate the effects of fish exposure in natural conditions. The results of present experiment did not show a relationship between the enzymatic activity and exposure to beta-blocker atenolol. This fact implies that the enzimatic reaction EROD, MROD and PROD cannot be useful as biomarkers reflecting a metabolic response of fish after exposure to this xenobiotic.
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The distribution of rainbow trout catches during the year with respect to stocking events
ČTRNÁCT, Petr
This bachelor thesis deals with the differences between the distribution of rainbow trout catches during the year on a different fishing grounds with respect to stocking events. Angler's records from the Svitava 1 and Blanice Vodňanská 4B fishing grounds were used and elaborated for these purposes. This thesis evaluates the rate of rainbow trout return and the ratio between stocking weight and catch weight in angler's records.
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Food competition between stocked hatchery reared rainbow trout and native brown trout and grayling
BLASZCZOK, Roman
The aim of the work will be based on the diet composition monitoring of the introduced rainbow trout and wild brown trout and grayling in defined time intervals, and assessing the degree of the food competition among the monitored species. The experiment was held in the second half of September 2010 in the river Blanice in the protected fish areas close to the village Těšovice, where several dozens of rainbow trout were stocked. In a predefined several - day interval of were caught 30 pieces of the rainbow trout (SL = 266 ? 14 mm, m = 347 ? 54 g), 33 brown trout (SL = 244 ? 19 mm, m = 219 ? 51 g), 14 graylings (SL = 256 ? 27 mm, m = 240 ? 91 g) and 12 resident rainbow trout (SL = 255 ? 13 mm, m = 280 ? 47 g) originated from the last plant. Within these groups a fish stomach content and consequently food selectivity was examined by using of the Ivlev's selectivity index (1961), a food competition was examined by using of the Schoener's index food overlap (1970) and the importance of various food components was examined by using of the index of preponderance according to Natarajan (1961). Rainbow trout began to ingest food immediately after the stocking into the stream and its occurrence was seen in all fish crop caught during the period. The insect (Insecta) was given as a preferential food of the rainbow trout and according to the index of preponderance (IP), it formed 54%, Trichoptera (IP) 24% and Ephemeroptera (IP) 19% orders belonged to the most preferable kinds of the food. According to the index of preponderance, gastropod (Gastropoda) formed (IP) 25% of a secondary food. The rainbow trout was accepting the same dietary components as well as the original sorts of salmonoid fish within the river. According to the index of a food overlap (S), the food competition between rainbow trout and brown trout was equal to the value of (S = 0.566) during the whole monitored period and the grayling was equal to (S = 0.520). Even though both of these values are slightly below the significant food overlap (S = 0.6), we can still say that the food competition is relatively high among these kinds.
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FORAGING ADAPTATION RAINBOW TROUT IN NATURAL STREAM
BLINKA, Tomáš
Goal of this study was to evaluate content and quantity of nourishment received by rainbow trout in defined time intervals after stocking to experimental segment of the Blanice river. Determine how fast the trouts raised in artificial breeding will adapt to biotic and abiotic factors in the stream and start ingesting in higher amount their natural nourishment. Rainbow trouts (SL= 266 ? 14 mm, m= 347 ? 54 g) were stocked in number of about a hundred of specimens into three segments of the river Blanice. These segments were connected and the fish were caught by agregat in beforehand determinated intervals. The nourishment of caught fish was analysed afterwards. We discovered that the fish started hunting after their natural prey nearly immediately after stocking. Natural nourishment were in the same amount as in the original fish as soon as three days after stocking. The nourishment of the fish in all monitored period was primarily composed of bentic organisms, according to index of preponderance (%) it was consisted of Caddisflies (Trichoptera) 24%, Mayflies (Ephemeroptera) 19% and the secondary element was composed of bigger terrestric prey as gastropods (Gastropoda) 25%, which got into the stream with rainfall water.
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Effects of triazine based pesticides on fish
MALÝ, Vratislav
Influence of triazine based pesticide (Sencor 70 WG - active substance metribuzine) was assessed via biochemical and hematological blood profile determination of experimental fish. As experimental fish we used common carp (Cyprinus carpio L.) and rainbow trout (Oncorhynchus mykiss ). Before rating the Sencor 70 WG pesticide influence on biochemical and hematological blood profile we accomplished a preliminary test to determine a concentration range and after that a basic acute toxicity test to determine 96hLC50 value. Both fish samples fingerlings were used for performing the tests. After 96hLC50 determination two groups of experimental fish (aged 1-2 years) were under this concentration and one control group without the substance. The test was processed according to the OECD methodology No. 203. Fish dissection was performed after the test. The increased amount of phlegm of water consistency on the body surface was found out. The fish were of dark colour in contrast with the control group. The ventricle was larger and containing transudate. An outstanding vascular profusion of internal organs in the ventricle was found out. Biochemical profile of the rainbow trout (Oncorhynchus mykiss ) experimental group under 96 hour acute operation of pesticide Sencor 70 WG (89,3mg.kg-1) proved significant lowering (p<0,01) of total proteins (TP), triglycerides (TRIG), aspartate aminotransferase (AST), amonnia (NH3), alcaline phosphatase (ALP) and Ca2+ in the blood plasma in contrast with the control group. Hematological profile of the same group proved significant lowering (p<0,05) of the number of erythrocytes (Er), haematocrit (PCV), and significant increase (p<0,05) of erythrocyte haemoglobin (MCH) value in contrast with the control group. Biochemical profile of the common carp (Cyprinus carpio L.) experimental group under 96 hour acute operation of pesticide Sencor 70 WG (250,2 mg.l-1) proved significant lowering (p<0,01) of total proteins (TP), triglycerides (TRIG), lactate dehydrogenase (LDH), Ca2+ and inorganic phosphate (PHOS) and significant increase (p<0,01) of glukose (GLU) and amonnia (NH3) concentration in the blood plasma in contrast with the control group. Hematological profile of the same group proved significant lowering (p<0,01) of the haematocrit (PCV), erytrocyte haemoglobin (MCH), mean erytrocyte volume (MCV) and number of leukocytes (Leuko) in contrast with the control group.
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