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„Peracetic acid, an alternative to
fight fish ectoparasites!?“
T. Meinelt 1, D. Straus 2, S. Matzke 3, E. Sudova 4
1 WGL - Leibniz-Institute of Freshwater Ecology and Inland Fisheries, Dept.
Aquaculture and Ecophysiology, Berlin, Germany2 USDA, Harry K. Dupree - Stuttgart National Aquaculture Research Center
Stuttgart, AR, USA3 Humboldt-University of Berlin, Germany 4 Research Institute of Fish Culture and Hydrobiology, Vodnany, Chech Republic
Structure
� Background of the PAA investigations
� About PAA
� Saprolegnia parasitica
� Ichthyophthirius multifiliis
� Life stage sensitivity to PAA
� Long term treatment of I. m.
� Mixed infection in Leuciscus idus
� Summary
� Chloramine-T
� Copper sulfate
� Florfenicol
� Formalin √
� Hydrogen peroxide √
� OTC
� Peracetic acid √? Water treatment? (Desinfection?)
� Potassium permanganate
� Salt (Sodium chloride) √
� Sodium hydroxide √
� Sodium monopersulfat
� Sodium percarbonate
� Unhydrated lime (Calcium oxide) √
Legislation, approved therapeutic agents.
Another European disaster
(Background of the PAA-investigations)
H3C C
O
OH
O O
H
H
O
H H
+ +H3C C
O
O OH
H3C C
O
OH
O O
H
H
O
H H
+ +H3C C
O
O OH
PAAC2H4O2 H2OH2O2
Disadvantages of PAA
• Thermodynamic instability (alteration of dosage).
• Modified effectiveness/toxicity in relation to water parameters such as
hardness, organic load, aeration etc.
• Corrosive.
• Caustic.
• Oxidizing effects, even at low temperatures.
• Very good water solubility.
• PAA-degradation produces acetic acid and hydrogen peroxide.
• The unspecific effects of PAA prevent the adaptation of microorganisms.
Advantages of PAA
Decrease of PAA (Wofasteril) concentration at 22°C,
Static, without aeration (doubled)
0
1
2
3
4
5
6
7
0 1 2 3 4 5 6 7 8
time [h]
ppm PAA
2 ppm
2 ppm (2)
3 ppm
3 ppm (2)
4 ppm
4 ppm (2)
5 ppm
5 ppm (2)
6 ppm
6 ppm (2)
Decrease of PAA (Wofasteril) concentration at 22°C, with aeration
0
1
2
3
4
5
6
7
8
0 1 2 3 4 5 6 7time [h]
ppm PAA
2 ppm
3 ppm
4 ppm
5 ppm
6 ppm
Decrease of PAA (Wofasteril) concentration at 30°C, without aeration
0
1
2
3
4
5
6
7
0 1 2 3 4
time [h]
ppm PAA
2 ppm
3 ppm
4 ppm
5 ppm
6 ppm
Selected results
Saprolegnia parasitica
Damages caused by Saprolegnia p.
(germ-carrier-investigations with D. rerio-eggs, germ-carrier (fungus media) = GY-agar Ø 10 mm infected
with S. p.)
Germ-carrier, GY-agar, 10 mmwith S. p. 14 d
Danio-rerio-embryos, 24 h, germ-carrier-test, no PAA-application
(negative control)
Danio-rerio-embryos, 24 h, germ-carrier-test, PAA-application, 3 ppm PAA, 2 h/d
Negative control
Treatment3 ppm PAA
(750 µL/100 L Wofasteril E400)2 x 1 h daily
Rainbow trout-eggs, fertilized
12
34
56
78
910
1112
0
100
200
300
400
500
600
Number of living eggs
days
control
2x10 min (4 ppm PAA)
2x1 h (3 ppm PAA)
12
34
56
78
910
1112
0
100
200
300
400
500
600
Number of infected eggs
days
eggs 2x1 h (3 ppm PAA)
2x10 min (4 ppm PAA)
control
Rainbow trout-eggs, fertilized,
Treated with Wofasteril E400,
3 ppm PAA (2 x 1 h) or 4 ppm PAA (2 x 10 min)
Number of
surviving eggs
Number of infected
eggs
Picture Daniel Hühn
Lifecycle of
Ichthyophthirius multifiliis
PAA to treat PAA to treat Ichthyophthirius multifiliisIchthyophthirius multifiliis
therontstheronts
Survival of I. multifiliis-theronts, treated with 0.2 ppm PAA
0
5000
10000
15000
20000
25000
30000
35000
40000
45000
[n / 100 mL]
2 10 19 39 58 68 77 92 111 118 127 133 138 142 186
t [min]
Control
0.2 ppm PAA
Survival of I. multifiliis-theronts, treated with 0.3 ppm PAA.
Theronts are treatable even at very low PAATheronts are treatable even at very low PAA--concentrations! concentrations!
t [min]
0
5000
10000
15000
20000
25000
30000
35000
[n / 100 mL]
2 14 16 23 33 41 53 111 120
Control
0.3 ppm PAA
PAA PAA vs.vs. Ichthyophthirius multifiliisIchthyophthirius multifiliis
trophontstrophonts
Trophonts
Dose-response relationship between percent of dead and live trophonts or tomonts in the detached trophont toxicity experiment. 48 h static treatment with PAA (Meinelt et al., subm.).
0%
10%
20%
30%
40%
50%
60%
70%
80%
90%
100%
Control 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9
mg/L PAA
Deadorlive trophonts and/ortomonts
live
dead
„Young“ trophonts (2.5 h)
0
100
200
300
400
500
600
700
Control 0.5 1 2 3
mg/L PAA
Live theronts per mL
Mean number of live theronts (± SD) produced from trophonts allowed to settle 2.5 h and then treated with 0, 0.5, 1, 2 or 3 mg/L PAA for 12 h. All exposed groups were significantly different from control (p<0.05).
12 h static treatment with PAA.Total incubation time 48 h.
„Old“ trophonts (tomonts)
0
200
400
600
800
1000
1200
1400
Control 0.5 1 2 2.5 3 0.5 1 2 2.5
0 2 2 2 2 2 4 4 4 4
Live theronts per mL
mg/L PAA
time [h]
Mean number of live theronts (± SD) produced from tomonts (24 h) treated with 0, 0.5, 1, 2, 2.5 or 3 mg/L PAA for 2 or 4 h. Total incubation time was 48 h.
Trophonts allowed to settle 24 h
„Dynamic“ 4 d-treatment
0
0,5
1
1,5
2
2,5
3
3,5
4
Gills Skin Fin
Mean infestation [n parasites]
Before PAA exposure
Control not PAA-exposed
After PAA exposure group (I)
After PAA exposure group (II)
PAA treated fish showed lower infestation with I. m. than the non-treated control fish as well as the I. m.-infected fish before PAA-exposure.
Investigations with wholesale ornamental fish. 600 fish (8 – 13 cm) from winter ponds, tanks volume = 1.2 m3, elevated mortality of 6 - 9 %/d
Diagnostics: Leuciscus idus [n = 20] Caudale, 40x, Chilodonella, Trichodina,
Epistylis, Ichthyobodo spp.
0 parasites
1-3 parasites
4-11 parasites
>11 parasites
0%
10%
20%
30%
40%
50%
60%
70%
80%
90%
100%
Chilodonella sp. Trichodina sp. Epistylis sp. Ichthyobodo sp.
0 parasites
1-3 parasites
4-11 parasites
>11 parasites
Results: Low infestion after threefold PAA-application
Leuciscus idus [n = 20] Caudale, 40x; 2.0 – 2.6 ppm PAA (6.5 mL WS), 1 x daily, 3 d,
Success: Chilodonella, Trichodina and Epistylis, moderate success with
Ichthyobodo; radical reduction of the losses.
0%
10%
20%
30%
40%
50%
60%
70%
80%
90%
100%
Chilodonella sp. Trichodina sp. Epistylis sp. Ichthyobodo sp.
0 parasites
1-3 parasites
4-11 parasites
>11 parasites
No treatment success
Ichthyobodo (Apistogramma, L. idus)
Dactylogyrus sp. (Koi-carp)
Oodinium sp. (Ctenopoma weeksi)
PAA-sensitive species
� Pikeperch (Lucioperca)
� Tench
� Several ornamental species
At the end of the story…
Therapeutical success:
� Chilodonella sp. (L. idus)
� Trichodina sp. (L. idus)
� Epistylis sp. (L. idus)
� Gyrodactylus sp. (Guppy)
� Ichthyophthirius-theronts, early trophonts (in vitro)
� Saprolegnia parasitica (in vitro, in vivo)
Summary
� PAA is instable with a high / variable toxicity.
� Data about altering factors (DOC?) is insufficient.
� Toxicological data for PAA is insufficient.
� The therapeutic index for some fishes / juveniles is low.
� For some parasites (e.g. Chilodonella, Gyrodactylus,
Trichodina) short time exposures are successful.
� Some stages of Ichthyophthirius are treatable.
� But, hatch of trophonts / theront is not synchronous.
� Therefore a long term exposure is necessary.
� Concentrations must be kept constant.
� Additional research concerning PAA-tolerance of fish
species, parasite species and developmental stages,
application intervals and PAA-concentration is necessary.
„Peracetic acid, an alternative to
fight fish ectoparasites!?“
„Yes”
Particularly in Germany/EuropeN
Thank you for your attention!
The investigations were
supported by the Schreiner-
Stiftung, Germany
But!Nominal concentrationTap water without organic materialGreat differences between species and ages
Toxicity of PAA
Danio rerio (Embryos) 48-h-LC50 2,8 ppm PAA
Cyprinus carpio (Embr.) 24-h-LC50 6,1 ppm PAA
Sander lucioperca (ZV) 24-h-LC50 1,14 ppm PAA
2
2,5
3
3,5
4
4,5
5
5,5
6
72 96 120 144 168
hours
ppm PAA
Wofasteril E250
Wofasteril E400
Dilution test Saprolegnia parasitica
Water desinfection
� Sodium hypochloride