Production of cyprinids for re-stocking purposes - Part 3. Controlled larval rearing conditions
European Network for the Dissemination of Aquaculture
RTD Information (Q5CA-2000-30105) and previously FAIR-3837, Aquaflow ref. :
TL2003-202
In the last few years, great development in the
rearing of fish larvae techniques has been observed. However, for many fish
species, methods of juvenile production for re-stocking are still poorly
defined. They require the study of many zootechnical aspects, including (in
this project) larval density, optimal temperature and food regimes.
Embryos
of wild cyprinids: asp (Aspius aspius), ide (Leuciscus idus),
dace (Leuciscus leuciscus), chub (Leuciscus
cephalus), nase (Chondrostoma
nasus), vimba bream (Vimba vimba)
and barbel (Barbus barbus) were kept at different temperatures for
observation of yolk sac absorption, pigmentation and swim bladder inflation.
Embryos were kept at four different temperatures: 10, 15, 20 and 25°C. Differences between temperatures, as well as between species,
were observed in all of the noted characteristics. A similar difference was
observed between embryos of asp, ide and dace and chub and is most probably
due to their similar embryo size and similar yolk sac size. These
differences were most apparent in nase (largest) and vimba bream (smallest)
larvae.
The
optimal density for rearing larvae under controlled conditions was between
40 to 100 larvae per liter. It was estimated at optimum temperature level,
which was 25–28°C. The biggest differences were observed when feeding
regimes were studied. Larvae of barbel and nase are fed initially with
commercial dry feeds, as used for trout or carp. Other species need a period
of feeding with live (i.e. Artemia nauplii) and mixed food. For asp,
chub, dace and ide, 8 to 12 days of live food feeding is required. Vimba
bream larvae need the longest period of feeding using live food. Shorter
periods of live food feeding give rise to high levels of mortality, as well
as some morphological abnormalities. Larvae of different species prefer
different commercial dry food: i.e. larvae of asp grow better on trout feed;
larvae of vimba bream on carp feeds. Larval survival was generally very
high, especially in the case of barbel and nase. During three weeks of
rearing, in all cases the survival rate was over 90%.
For more information, contact:
KUJAWA Roman
Department of Lake and River Fisheries
Warmia and Mazury University in Olsztynul. Oczapowskiego 2
10-718 Olsztyn-Kortowo
Poland
Phone : (48 89) 5233436
Fax : (48 89) 5233969
e-mail: reofish@moskit.uwm.edu.pl