1 August 1999
MALACHITE GREEN AND ALTERNATIVES TO CONTROL FUNGAL INFECTIONS
Date: 20 July 1999
From: Duncan.Perrin@marine-harvest.co.uk
To: aqua-l@killick.ifmt.nf.ca
QUESTION :
Can anyone provide me with any information or contacts regarding malachite green alternatives with a view to controlling fungal infections in ova and fish? I am particularly interested in salmonids, but information on other fish species would also be useful. I am not necessarily interested in commerically sensitive information, just an overview of what people are using.
The background to my request is that malachite green is about to be banned in the UK and I know that it has been banned in the USA for a while, and what do people think is the most useful alternative. We have (West Coast of Scotland) a problem with the post-vaccination of smolts, the immune response is lowered and the fish become very susceptible to infection, which usually takes the form of a fungal infection.
Duncan Perrin
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COMMENTS 1 :
We have used salt bath treatments for the control of fungal infections in juvenile salmonids. It's not as effective as malachite, but at least it's
not carcinogenic, and it is readily available.
Terrence Nicholls
Department of Fisheries and Oceans
Science Branch
PO Box 5667
St. John's, Newfoundland, Canada
A1C5X1
Tel. 709-772-4514
Fax. 709-772-3578
e-mail : Nichollst@dfo-mpo.gc.ca
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COMMENTS 2:
Contact to Dr. Andras Woynarovich: awoy@citecho.net
He used tannic acid for this purpose.
Peteri Andras <peteri@mail.datanet.hu>
Tel/Fax:00 36 63 453 509
6621 Derekegyhaz Pf.25
Hungary
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COMMENTS 3:
We have used formalin and salt treatments to help control fungal infections. Should try to get a hold of John Holder (JHOLDER@ISLAND.NET) for a formalin regime after vaccination that he claims is the magic potion.
Caroline Cherry
<ccherry@island.net>
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COMMENTS 4:
We use malachite green for fungal infections but it is extremely hard
on fish. We have fresh water game species indigenous to Minnesota. We also use it to treat the bait fish we use for feed. The concentrations we use are 1ppm. We have also used it on Ich with success. The only problem we have found is that malachite green can block an enzyme used in digestion and fish can go off of feed for a certain amount of time.
Because of the harshness of malachite green, we only use it in extreme
cases. We now use formaldehyde at 250ppm and salt. People may tell you that malachite green is a carcinogen but isn't everything else? It only becomes a carcinogen when you feed it directly to your fish in concentrations that you would never normally do.
Malachite green, as far as I know, has not yet been banned in the
public aquarium realm which is where we use it.
Sheldon Langager
Aquarium Curator
Cabela's Retail Inc.
Owatonna, MN
e-mail : langager@ll.net
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COMMENTS 5 :
Here are some malachite green alternatives (antifungals) for your
consideration.
1. Formalin. Permitted use in the US is up to 170 ppm for 1 hr @ >50 F; up to 250 ppm @ <50 F. Retreat after 5 days.
2. Hydrogen peroxide. Permitted use in the US as "low regulatory priority" on fish and eggs at 250-500 mg/L (100% active) for 15 minutes every-other-day.
3. Sodium chloride. "Low regulatory priority" use in the US is at 3% for 10-30 minutes.
The following are unregistered for use in the US:
1. Tannic acid bath, 10-40 g/L, twice per week, for 1 hour each.
2. Quaternary ammonium, 2 ppm active for 1 hour for 3-5 days.
There are others as well. The important thing is to use caution for both
humans and fish. Test it on a few fish/eggs first and do not overdose. Check with local authorities for chemical use restrictions.
Kent Hauck
Fish Pathologist
e-mail : agmain.khauck@state.ut.us
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COMMENTS 6:
I refer you to: Kojima,Hiroshi. 1978. Effects of Tannic Acid on Aquatic Fungi Associated with Diseases of Fish Eggs. Reprinted from Scientific Reports of the Hokkaido Fish Hatchery, No 33, pp 45-53. (Abstract, tables and figures in English).
This report indicates results of experimentation with tannic acid as
follows: -TLm (median tolerance limit) for tannic acid on eyed eggs of steelhead trout was approximately 170 g/l (170,000 ppm)
-Saprolegnia was effectively controlled water hardened chum salmon eggs bathed at 1 and 10 g/l twice per week for 1 hr. Hatching rates were 98% and 97% respectively.
-Survival of eyed steelhead eggs was 97% for both 20 g/l and 40 g/l.
Survivals diminished at higher concentrations.
Kent Hauck
e-mail : AGMAIN.KHAUCK@STATE.UT.US