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¹ National Agricultural Research and Innovation Centre, Fisheries Institute (NARIC HAKI), Szarvas, Hungary
² Kaposvár University, Faculty of Agricultural and Environmental Sciences, H-7400 Kaposvár, Guba Sándor u. 40, Hungary DOI : 10.4194/1303-2712-v17_3_02 Viewed : 4294 - Downloaded : 4716 The methods for removal of adhesiveness in pikeperch eggs were compared in this study. Following the hormonal induction with carp pituitary, eggs of three females were used in each of two trials. Firstly, three common methods were tested: tannic acid, enzyme and milk. Tannic acid treatment led to poor hatching (2.5±0.5%), significantly lower than the other treatments (75.5±19.3% and 72.3±28.8%, enzyme and milk, respectively). In order to find the source of negative outcome, in the second trial the influence of water hardness on the tannic acid bath was tested through three treatments with varying concentrations of disodium ethylenediaminetetraacetic acid salt (NA2EDTA). Softening of the tannic acid bath did not lead to improved hatching rates (5.5±1.3%, 3.5±1.5% and 2.7±1.3% for 0, 400 and 800 ppm of EDTA, respectively). Evaluation of the effects of tannin and EDTA on water chemistry revealed that the use of tannin can alter the embryonic development and hatching process. While de-adhesion procedure with milk appeared to be impractical, the application of tannic acid bath leads to variable and lower hatching outcomes. Thus, usage of enzymes was found to be the most promising method which should be further described for straightforward implementation in practice. Keywords : Hatching, tannin, enzymes, milk, water hardness