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Length and weight growth of early pikeperch fry fed with enriched artemia nauplii in experimental conditions
JANKOVÝCH, Antonín
The aim of our experiment was proving the suitability and effectivity of artemia nauplii enrichment in pikeperch fry rearing. 24 hour enrichment took place in 3 variants: 1. SELCO, 2. 18 (n-3) (alfa-linolenic acid) and 3. 18 (n-3) + vitamin C. Original intention was initializing fry feeding with different types of enriched artemia metanauplii. Due to excessive size of artemia after 1 day enrichment (Artemia franciscana) (in comparison with size of fry oral cavity) the intake of such food was not possible, thus the metodics had to be modified. From the given reason, fish were initially fed with unenriched nauplii ; firstly with dose 100 ml (4 - 8 day post hatch - dph) after that with dose 50 ml per tank (9. dph 25.4.). As soon as fry reached suitable size and was able to intake bigger size of nauplii, was in the second part feeding diferenciated (use of different types of enrichment and control group was fed with unenriched artemia). First part of experiment lasted 22 days (5.4. - 26.4.), fish must have been netted and again placed in tanks for experiment with enriched artemia. Second part of rearing varied in use of differently enriched metanauplii and lasted 8 days (27.4. - 4.5.). At the end of second part of feeding (from 1.5.) was involved co-feeding, which means combined feeding (living food and starter feed). 5.5. was experiment terminated. The highest survival was reached in group fed with artemia enriched in comercial preparate SELCO (28,67 %), second highest survival was reached in group fed metanauplii enriched in alfa-linolenic acid (27,88 %) and third highest survival was reached in group fed with alfa-linolenic acid and vitamin C enriched metanauplii (19,00 %). The highest individual fry weight at the end of experiment was reached in group fed with artemia enriched in alfa-linolenic acid and vitamin C : 306,16 +- 64,27 mg, the lowest individual weight was reached in control group : 216,9 +- 39,96 mg. The highest average total lenght (l.t.) was measured in SELCO group 30,13 +- 2,47 mm, the lowest total lenght reached fish in control group 27,37 +- 1,32 mm. In group fed with artemia enriched in vitamin C was noticed the highest percentage of starter feed intake (8 %), but simultaneously in the same group was reached the highest rate of cannibalism (6 %).
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