small septum. However, the majority of the retrieved isolates
(7/10 isolates) showed identical morphological characteristics
of Saprolegnia’ sexual reproduction such as terminal oogonia
with centric oospores and antheridia (Fig. 1).
3.2. PCR and phylogenetic analysis
A 750 bp fragment was amplified from high-quality DNA extracted
from 10 isolates using primers targeting the ITS gene
(Fig. 2). The 10 ITS region’ sequences achieved from the highest-
scoring segment pairs from the BLAST search using the
ITS region sequence were from S. parasitica. The ITS region
sequence from S. parasitica ATCC90213 (GenBank Accession
No. AY455771) showed 99% identity to the portion of the
PCR fragment containing the ITS region sequences. The phylogenetic
analysis using neighbor joining method showed that
the amplified sequences were grouped with known sequences
of S. parasitica and separated from other groups belonged to
Saprolegnia hypogyna, Saprolegnia diclina and Saprolegnia longicaulis
(Fig. 3)
3.3. Field trial evaluation of povidone iodine
The used concentrations of 60 mg L1 povidone iodine for
30 min as initial dose followed by a maintenance dose of
70 mg L1 for 10 min as rinsing solutions for spawner angelfish
has proved its disinfectant efficacy against the mould infection.
Egg wise, 60 mg L1 for 30 min as an immersion solution
for eggs was very efficient to combat mould infection among
egg stocks. These conclusive results were confirmed by inability
to retrieve the water mould back from the treated angelfish
spawners and their eggs. Such disinfection protocol has resulted
in an abrupt decline of spawner angelfish and their
egg mortalities. Number wise, the mortality rates of incubated
eggs were abruptly declined from 70% to 30%, while hatching
rate had sharply increased from 10% to 60% within one week
post treatment.