Peracetic acid, an alternative to fight fish ectoparasites!?

Transcription

1 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, Germany 2 USDA, Harry K. Dupree - Stuttgart National Aquaculture Research Center Stuttgart, AR, USA 3 Humboldt-University of Berlin, Germany 4 Research Institute of Fish Culture and Hydrobiology, Vodnany, Chech Republic

2 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

3 Legislation, approved therapeutic agents. Another European disaster (Background of the PAA-investigations) 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)

4 Advantages of PAA 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. 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. H3C C O H O + O O H3C C + O OH H O OH H H C 2 H 4 O 2 H 2 O 2 PAA H 2 O

5 Decrease of PAA (Wofasteril) concentration at 22 C, Static, without aeration (doubled) ppm PAA ppm 2 ppm (2) 3 ppm 3 ppm (2) 4 ppm 4 ppm (2) 5 ppm 5 ppm (2) 6 ppm 6 ppm (2) time [h]

6 Decrease of PAA (Wofasteril) concentration at 22 C, with aeration 8 ppm PAA ppm 3 ppm 4 ppm 5 ppm 6 ppm time [h]

7 Decrease of PAA (Wofasteril) concentration at 30 C, without aeration 7 6 ppm PAA ppm 3 ppm 4 ppm 5 ppm 6 ppm time [h]

8 Selected results Saprolegnia parasitica

9 Damages caused by Saprolegnia p. (germ-carrier-investigations with D. rerio-eggs, germcarrier (fungus media) = GY-agar Ø 10 mm infected with S. p.) Germ-carrier, GY-agar, 10 mm with S. p. 14 d

10 Danio-rerio-embryos, 24 h, germ-carrier-test, no PAA-application (negative control)

11 Danio-rerio-embryos, 24 h, germ-carrier-test, PAA-application, 3 ppm PAA, 2 h/d

12 Rainbow trout-eggs, fertilized Negative control Treatment 3 ppm PAA (750 µl/100 L Wofasteril E400) 2 x 1 h daily

13 600 Rainbow trouteggs, fertilized, Treated with Wofasteril E400, 3 ppm PAA (2 x 1 h) or 4 ppm PAA (2 x 10 min) Number of living eggs control 2x10 min (4 ppm PAA) 2x1 h (3 ppm PAA) days Number of surviving eggs eggs 2x1 h (3 ppm PAA) 2x10 min (4 ppm PAA) Number of infected eggs control Number of infected eggs days

14 Lifecycle of Ichthyophthirius multifiliis Picture Daniel Hühn

15 PAA to treat Ichthyophthirius multifiliis theronts

16 Control 0.2 ppm PAA [n / 100 ml] t [min] Survival of I. multifiliis-theronts, treated with 0.2 ppm PAA

17 Control 0.3 ppm PAA [n / 100 ml] t [min] Survival of I. multifiliis-theronts, treated with 0.3 ppm PAA. Theronts are treatable even at very low PAA-concentrations!

18 PAA vs. Ichthyophthirius multifiliis trophonts

19 Trophonts 100% Dead or live trophonts and/or tomonts 90% 80% 70% 60% 50% 40% 30% 20% 10% 0% live dead Control mg/l PAA 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.).

20 Young trophonts (2.5 h) 700 Live theronts per ml h static treatment with PAA. Total incubation time 48 h. 0 Control mg/l PAA 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).

21 Old trophonts (tomonts) 1400 Live theronts per ml Trophonts allowed to settle 24 h 0 mg/l PAA time [h] Control 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.

22 Dynamic 4 d-treatment 4 Mean infestation [n parasites] 3,5 3 2,5 2 1,5 1 0,5 Before PAA exposure Control not PAA-exposed After PAA exposure group (I) After PAA exposure group (II) 0 Gills Skin Fin 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.

23 100% 90% 80% 70% 60% 50% 40% 30% 20% 00 parasites 1-3 parasites 4-11 parasites >11 parasites 10% 0% Chilodonella sp. Trichodina sp. Epistylis sp. Ichthyobodo sp. Investigations with wholesale ornamental fish. 600 fish (8 13 cm) from winter ponds, tanks volume = 1.2 m 3, elevated mortality of 6-9 %/d Diagnostics: Leuciscus idus [n = 20] Caudale, 40x, Chilodonella, Trichodina, Epistylis, Ichthyobodo spp.

24 100% 90% 80% 70% 60% 50% 40% 0 parasites 1-3 parasites 4-11 parasites >11 parasites 30% 20% 10% 0% Chilodonella sp. Trichodina sp. Epistylis sp. Ichthyobodo sp. Results: Low infestion after threefold PAA-application Leuciscus idus [n = 20] Caudale, 40x; 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.

25 At the end of the story No treatment success Ichthyobodo (Apistogramma, L. idus) Dactylogyrus sp. (Koi-carp) Oodinium sp. (Ctenopoma weeksi) PAA-sensitive species Pikeperch (Lucioperca) Tench Several ornamental species

26 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)

27 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.

28 Peracetic acid, an alternative to fight fish ectoparasites!? Yes Particularly in Germany/Europe

29 Thank you for your attention! The investigations were supported by the Schreiner- Stiftung, Germany

30 Toxicity of PAA Danio rerio (Embryos) 48-h-LC 50 2,8 ppm PAA Cyprinus carpio (Embr.) 24-h-LC 50 6,1 ppm PAA Sander lucioperca (Z V ) 24-h-LC 50 1,14 ppm PAA 6 ppm PAA 5,5 5 4,5 4 3,5 3 Wofasteril E250 Wofasteril E400 2,5 But! Nominal concentration Tap water without organic material Great differences between species and ages hours

31 Dilution test Saprolegnia parasitica

32 Water desinfection Sodium hypochloride