Iraqi Journal of Aquaculture

The epiphytic algae were studied on three aquatic plants
(Ceratophyllum demersum, Myriophyllum verticillatum and Potamogeton
pectinatus) from seven stations in Euphrates River between Hindia
barrage and Al-Kufa city-Iraq, during summer 2004 and spring 2005.
A total of (97) species were identified, diatoms were dominant in their
species number (73% from the total number), followed by chlorophyta,
then cyanophyta and Euglenophyta. Variations were recorded in the
species number among the host macrophyte, as well as, among different
seasons for each plant. The biomass of epiphytic algae varied among the
plant host, diatoms species were dominated and several genera have large
number of species as Cymbella, Gomphonema, Nitzschia and Synedra.
Most studied stations showed high population density.

Some Iraqi plants which belonging to different families were
extracted in 80% Ethanol and the ability of these extracts to control and
growth of Cyanobacteria was evaluated. Results indicated that Artemisia
campestris, Achillia santolina, Artemisia herba-alba and Centurea
khotchii extracts were very active in inhibiting the growth of the test
Cyanobacterial species. However, other plants extracts in this study did
not show any promising algicidal potencies.

The effect of fish density and feeding rates on growth and
food conversion of gilthead seabream (Sparus aurata) was studied in
floating cages and fiberglass tanks in Sammaliah Island- Abu Dhabi.
The results of floating cages experiment showed that there was no
significant effects (p>0.) of fish density on growth and food
conversion rate but there are significant effects (p<0.05) on fish
production (4.11, 7.47 and 10.08) kg/m3 for densities (50,100 and
150) fish/m3 respectively. No significant differences between weight
ranges [(27-125), (21-142), (30-126)] g of these fish at the end of
experiment, and also between final weights (82.3, 77.4, 67.2) g for
densities (50,100,150) fish/m3 respectively. The results of fiberglass
tanks experiment showed that there are no significant effects of
feeding rate on growth, while there are significant effects on the
food conversion rate (1.43, 2.86 and 3.71) for feeding rates (5, 7.5
and 10)% of fish weight respectively. Floating cages give better
results from fiberglass tanks (growth rate 0.64 g/day compared with
0.4 g/day, final production 7.31 kg/m3 compared with 4.58 kg/m3
and final weight 75.6 g compared with 45.8 g).

The larvae of grass carp Ctenophargodon idella were fed on
three types of live food Brachionus calyciflorus, Artemia sp. and
Daphnia magna. The study showed that live food is very important
to achieve high growth and survival of fish larvae. The average
weights of C. idella fed on B. calyciflorus were 118.12+3.0 mg /
larvae and 29.48+0.8 mm / larvae respectively, and in case of
Artemia sp. The rates were 103.13+1.5 mg/ larvae and 25.34+1.4
mm / larvae, while in the mixed food the rate were 122.80 + 1.8
mg / larvae and 30.08 + 1.1mm /larvae .The survival rate was
better on B. calyciflorus treatment as it was 98.6 % ,while it was 98
% and 97% in case of mixed food and Artemia sp. Respectively .

Soya bean was replaced in ratio of 20% and 40% by a dry
duck weed in the diet of common carp fry under laboratory
conditions. The results showed that the fry which fed on duck
weeds gives a final total length of 40.15mm, final wet weight of
1.105 gm and final increase of weight was 0.966gm. The group of
larvae which fed on soya bean recorded 37.230 mm, 0.750 gm and
0.618 gm respectively.

The seasonal variations in algal compositions quantitatively
and qualitatively have been studied for two stations in Alwnd
River, represented before and after passing Khanqeen city through
eight months starting in December 2000. A total of 123
phytoplankton taxa were identified, dominated by diatoms (63
species) followed by greens (34 species), blue-greens (15 species)
and 11 species for other groups. The total cell number of
phytoplankton ranged between 34565 and 37940 cell/cm3 in both
stations with two peaks in spring and summer. The higher density
of cell number and species was recorded in the second station
during the studied period.