ABSTRACT
Commercial production of rotifers normally occur in batches of approx. 6 days, which pass through a phase of exponential production and towards the end: reduced production caused by deteriorating water quality and otherwise suboptimal conditions.
A carefully monitored feeding regime may reduce water quality problems to an acceptable level: some production can be maintained throughout the batch period.
Still we annually experience several periods with tendencies of culture chrash. If the resulting rotifers are used to inoculate the next batches, the result is low or no production and variable rotifer quality.
At Tinfos Aqua we use a strain of Brachionus plicatilis with a body length of approx. 300 μm, grown in full salinity (approx. 30 %.) at 23°C and fed a mixture of bakers yeast and marine oil.
By reducing batch duration from 6 days to 2 days, daily feeding could be increased from 0.8 g mix/mill, to 1.1–2.0 g mix/mill.
Daily production then increased from approx. 15–20 % to 40–90 %, making the loss (approx. 10 %) during more frequent sieving/r insing acceptable.
2-days batches showed no culture chrashes during 2 years: a stable production was maintained through periods when the 6-days batch cultures chrashed.
Individuals grown in 2-days cultures showed greater and more stable appetite and greater tolerance against stress.
Greater stress resistance permitted increased aeration which further improved tank milieu: a higher and more stable O2 level and less sedimentation of food particles.
