Nitrogenous and phosphorus excretions in juvenile

Authors: Jaqueline Ineu Golombieski Gessi Koakoski Alessandra Janaína Becker Ana Paula Gottlieb Almeida Cândida Toni Isabela Andres Finamor Maria Amália Pavanato Tielle Moraes de Almeida Bernardo Baldisserotto

Publish Date: 2012/11/08

Volume: 39, Issue: 4, Pages: 837-849

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Abstract

This study examined ammonia urea creatinine protein nitrite nitrate and phosphorus P excretion at different water hardness humic acid or pH levels in silver catfish Rhamdia quelen juveniles The fish were exposed to different levels of water hardness 4 24 50 or 100 mg L−1 CaCO3 humic acid 0 25 or 50 mg L−1 or pH 50 60 70 80 or 90 for 10 days The overall measured nitrogen excretions were 881  244–423 μmol kg−1 h−1 for ammonia 109  30–52 μmol kg−1 h−1 for creatinine 002  005–008 μmol kg−1 h−1 for protein 0001  0002–0004 μmol kg−1 h−1 for urea 05  064–36 μmol kg−1 h−1 for nitrite and 05  00–69 μmol kg−1 h−1 for nitrate and these proportions were not affected by water hardness or humic acid levels The overall P excretion in R quelen was 014–297 μmol kg−1 h−1 Ammonia excretion in R quelen usually was significantly higher in the first 12 h after feeding and no clear effect of water hardness humic acid levels and pH on this daily pattern of ammonia excretion could be observed Water hardness only affected the ammonia and P excretion of R quelen juveniles in the initial and fifth days after transfer respectively The exposure of this species to humic acid increased ammonia excretion after 10 days of exposure but did not affect P excretion An increase in pH decreased ammonia and increased creatinine excretion but did not change P excretion in R quelen Therefore when there is any change on humic acid levels or pH in the culture of this species nitrogenous compounds must be monitored because their excretion rates are variable On the other hand P excretion rates determined in the present study are applicable to a wide range of fish culture conditions

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