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Fish Juicing

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#1 anchar

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  • Joined: 28-January 04
  • Location: Bullcreek

Posted 13 September 2006 - 07:29 PM

Injecting Fish with Dye
by David Midgely

What is Juicing?

Juicing is the artificial colouration of fishes. Commonly juiced species include the so called “painted glassfish” along with albino varieties of a number of catfish and loaches. Some species, such as albino corydoras and so called “painted” glassfish are injected with dye using a hypodermic needle. A large number of fish reportedly do not survive this procedure. In fishes that do survive this process there is an 30% increase in diseases such as lymphocystis in “painted” varieties compared to wild type (unpainted) aquarium populations. This is presumably due to infection via dirty syringes between juicing.

For further information on juicing and the effects please see this excellent article by Dr. Jim Greenwood. Further information is also available in the well respected tropical fish hobbyists magazine, Practical Fishkeeping, who run a campaign against this practice. Practical Fishkeeping - Anti-Dyeing Campaign.

Artificially coloured fish have been available for a number of years - appearing first around 1980 (McMahon & Burgess 1998). The first fishes to be coloured were painted glassfish their transparent bodies providing a blank canvas for the dyers. More recently at least in Australia, albino corydoras that have been dyed blue, red, yellow or green have appeared in a number of stores.

In 1998 MacMahon and Burgess investigated how the dye was applied to the fish. A number of rumours circulate in hobby as to the exact method of application - not suprisingly this dubious practice is not well detailed, some maintain the dye is applied to the outside of the fish, while others speak of injection via hypodermic needle. To determine exactly how the dye was applied MacMahon and Burgess sedated several glassfish and examined them under a microscope. It was obvious to the authors that the dye was not outside the epidermis (the outer layer of cells), but under it. The authors comment that the dye remained fluid under the “skin” of the fish. The only way for this to have occured would be for dye to have been injected into the fish at a large number of points.

The authors go on to say that after viewing photographic evidence of this practice which is undertaken by fish farmers in Asia, the bore size of the needle is relatively large. Even if one considers a very small needle, the relative size of the needle to the small size of the fishes being injected - means that it would be similar to us receiving multiple injections with a pencil sized needle.

Burgess and MacMahon also carried out a survey of rates of infection of lymphocystis, a virus that causes small white growths on the body, in both painted and unpainted varieties of painted glassfish. They found an increase of almost 30% infection in painted varieties when compared with their undyed equivalents. They speculated that this increase in disease is presumably from transmission of the virus via unsterile needles. They also state that it may be due to decreased immune system function due to the stress of the injection process. There is also strong evidence in histological material of severe kidney trauma associated with the relatively large amounts of dye being injected. (Phillips, B. pers. comm.)

In time the dye fades, and the fish takes on normal coloration. Albino versions of Corydoras catfish, Tiger Barbs, Labeo “sharks”, Black widow Tetras, Albino loaches, blue oscars and ram cichlids have also provided a clean canvas for dying.

This is a cruel, unethical and immoral practice, which, given the range of beautiful tropical fish available in the fishkeeping hobby is completely unnecessary.

What do other people think of this practice?

The Australian RSPCA said:

…We have investigated the practice of dyeing fish through injection and have resolved that the procedure is unnecessary and has the potential to compromise the health and welfare of the fish. These effects may include the introduction of disease and the handling of the fish can compromise the protective antibacterial mucus layer on the surface of the fish. Although the RSPCA has no specific policy on this practice, it would be considered similar to the practice of surgical mutilation such as the tail docking of dogs: ‘RSPCA Australia is opposed to the mutilation of animals for cosmetic (non-veterinary purposes).’ This practice is certainly purely for cosmetic purposes only, is not necessary and can be potentially damaging to the fish. The RSPCA therefore would oppose this practice…Obviously what is required is a cultural change in the industry and the education of buyers that fish should not be dyed as there can be negative health effects on the fish…

What can I do?

Consumers/Hobbyists: If you see painted glassfish in an aquarium tell the owner or manager that this is a cruel practice. If enough people complain we can stop the sale of these fishes. The sad truth about dyed fish is that most often they are bought by people who are new to the hobby and would not suspect this practice. When new aquarists discover the truth about this practice they are normally saddened that they have been deceived into buying fish that are coloured for profit.

Aquarium Owners/Wholesalers: Contact me to be added to our list of juicing free aquariums.

Webmasters: Link to this article, spread the word.

Australian Retailers & wholesalers who have pledged NOT to stock dyed fish

I would like to thank all the aquariums and wholesalers listed below (in no particular order) who support the campaign to stamp out this practice. I actively endorse ALL of the following businesses and can RECOMMEND them to the new and advanced aquarist alike:

Boronia Aquarium (VIC)
Campelltown Pet & Aquarium Centre (NSW)
Marinelife Aquarium (NSW)
Profishionals Aquarium Group
Aqua Pets Aquarium (NSW)
Pets World (NSW)
Bay Fish (QLD)
Aquarium Industries (AI) (VIC)
Auburn Aquariums (NSW)
Aggies Aquariums (SA)
House of Fish (ACT)
The Pet Shop Around The Corner (QLD)
Gold Coast Aquariums (QLD)
St. George Aquariums (NSW)
Age of Aquariums (QLD)
Xtreme Aquariums (NSW)
Aquatic Life Aquariums (NSW)
Aquatic Wholesalers (NSW)
Wings & Fins Aquarium (NSW)


MacMahon, S. and Burgess, P. (1998) Why it’s cruel to dye. Practical Fishkeeping. March 1998. pg: 114-115.

Other websites with information on dyeing:

Painting Live Tropical Fish


Thanks to Roger Morrison for sending me the journal article on which much of the data provided is founded. Also I’d like to thank Dr. Bill Phillips for some information regarding kidney problems in dyed fish.

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