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Rearing of weatherfish (Misgurnus fossilis) fry in artificial condition
FRANTA, Pavel
The aim of the M.Sc. thesis was to verify possibility of weaning weatherfish larvae (Misgurnus fossilis) from the live food to the dry starter mixture using the method of co-feeding. The experiment included 3 control groups (starved control no feeding; negative control fed exclusively with dry starter mixture; positive control fed exclusively with live food) and 10 experimental groups with 5 different dates of termination of co-feeding period (at the age 13, 18, 23, 28 and 33 days post-hatching dPH) and different duration of co-feeding period (1 and 7 days). The experiment lasted from the 6 dPH, when mixed feeding was iniciated, until the age 48 dPH at the temperature of 17,8 +- 0,7 °C. The effects of termination and duration of co-feeding period upon continuous survival, morphometric and gravimetric characteristics, ratio of macrobiogenic elements and gross caloric value in somatic tissues of larvae/juveniles were evaluated. Continuous survival, morphometric and gravimetric characteristics and total content of carbon and nitrogen in somatic tissues of larvae/juveniles were increasing with extending dates of termination of co-feeding period. The rearing of weatherfish larvae was accompanied by the marked decline of survival in the period 13 20 dPH, regardless of selected diet regimes in individual groups. Within all fed groups, the worst results of continuous survival and growth were recorded in the negative control as well as groups with date of co-feeding period termination at age 13 dPH. All individuals in these groups died at age 41 dPH. At the end of the experiment, the highest values of continuous survival were achieved in the positive control as well as groups with dates of co-feeding period termination at age 23, 28 and 33 dPH, respectively. There was no significant statistical difference among these groups. Very good results in terms of morphometric and gravimetric characteristics were achieved in the groups with dates of co-feeding period termination at age 28 and 33 dPH, respectively. However, only in group with date of co-feeding period termination at age 33 dPH were achieved comparable values of morphometric characteristics with the positive control. The exception formed only values of the body height as well as dry and wet weights which were significantly higher in the positive control compared to other fed groups. The duration of the co-feeding period (either 1 or 7 days) did not affect any of the monitored characteristics. The results of the present thesis also show that the weatherfish fry best prospers on live food and, on the contrary, fry can not be reared using dry starter mixture as a sole food source. To sum up, among all tested groups that use co-feeding, only weaning of larvae with the date of co-feeding termination at age 33 dPH could be advised. In such condition the continuous survival rate as well as lenght growth reach comparable values with group exclusively fed by live food.
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