Variation of whole body amino acid profile in Eurasian perch Perca fluviatilis L. reared in an inorganic fertilized pond

Abstract

Ten thousand eggs of Eurasian perch ready to hatch were stocked in a cage in a pond where zooplankton population was abundant. The pond was fertilized at the beginning and every week until day 85, with superphosphate and ammonium sulphate to obtain 30 μg l-1 for phosphorus and 600 μg l-1 of nitrogen. This fertilization is known to maintain abundant zooplankton for fish growth, without low dissolved oxygen, high ammonia and pH occurring regularly in fertilized pond, due to blue-green phytoplankton bloom. Water quality was monitored through measurement of temperature, dissolved oxygen, pH, nitrogen, phosphorous and chlorophyll a. Samples of fish were analyzed on the Water Pico-Tag amino acid analysis system. For the study period, survival rate calculated after counting all survival fish reached 7.5%. Final fish body weight averaged 0.850 ± 0.678 g (measured for 600 fish), but some large fish reached up to 2.1 g. During the first week, specific growth rate of fish was very high (SGR = 38% day-1), and then decreased to 8.5% day-1 at harvesting. Average SGR for the whole period was 9.3% day-1. Except glycine, alanine proline and aspartine, whole body amino acid composition remained stable throughout the growing period.

Keywords: Water quality, zooplankton, fish growth, protein quality.