7145 ‎(2)‎

• UCREFRP Catalog Number: 7145
• Author: Inslee, T. D.
• Title: Spawning of Razorback Suckers
• USFW Year: 1981.
• Copyright Material: NO

.`.
M • .~
A five minute treatment of 1:50 formalin of three day old eggs sustained a 21%
loss and four day old eggs had a 7% loss.
It appears that the Lbo lies between 1:50 and 1:75 formalin for 5 to 10
minutes. The length of treatment time also affected the survival rate of
eggs.
Tests were also performed on two day old eggs but viable and nonviable
eggs were hard to seperate. The reduction of viable eggs was extremely dif-
ficult to ascertain but it appeared that 1:75 for. 5 and 10 minutes caused
no egg mortality.
The efficacy tests of formalin on the fungi growing on,.eggs was tested
:;f ter the fungi had been transplanted to hemp seed. After treatment of de-
veloping fungal infections the effect was noted after five days and 16 days.
• The rationale of these two time periods was to correspond to hatching and
fry swim-up time. Iff eggs are incubated in Heath trays the fry would hatch
and be removed from fungus in about a five day period but if eggs were incu-
bated in the circular tank method the fry would be exposed to expanding
fungus until they could swim up or about 14 days.
After five days from treatment the fungus appeared to be dead at concen-
trations of 1:75 and 1:100 for both five and ten minute treatments; also at
1:200 for 10 and 15 minute treatments. There were no new growth of mycelia
nor had any of the uninfected hemp seed in the tests developed any fungal
growths.
The treatment at 1:300 for 10 minutes did not show that the fungus had
been killed but its growth had been delayed to where it would not have pro-
Iiferated to other areas. Only one test showed reproductive organs developing
on the ten minute treatment and no development of reproductive products of
the 15 minute treatment.
15