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Related FAQs: Dips/Baths, Dips/Baths 2Dips/Baths 3, & FAQs on Dip/Bath: Rationale/Use, Methods, Tools, Adjusting pH, Additives, Iodine/ide/ate, Lugol's Use, Methylene Blue, Formalin/Formaldehyde, Dangers Will Robinson, Products, & Best Quarantine FAQs,

Related Articles: Methylene Blue, Formalin/Formaldehyde, Quarantine, Quarantine of Corals and Invertebrates, Tank Troubleshooting, Toxic Tank Conditions, Environmental Disease (incl. Lymphocystis), Nutritional Disease, Infectious Diseases, Parasitic Diseases, Wound Management (/aquarists), A Livestock Treatment System

/The Conscientious Marine Aquarist

Dips/Baths, A Useful Protocol for Excluding Many External Fish Parasites

By Bob Fenner

This crypt could have been prevented by a simple pH adjusted freshwater dip.

Are your new fish funky, gunky on arrival? Lethargic? Lack spunk, riddled with sores and spots? Well cheer up Bunky! We've got just the cure for you. Simply pour in X amount of New (!) EndAll! Never mind that this treatment is going to bring biological filtration to a grinding halt, use up all available oxygen, or that within twenty four hours the whole system will be toxic unless you do consecutive massive water changes... Problems? Call our direct help line 1-800-GO-FLUSH.

Does this sound at all familiar? Wouldn't removing harmful, external parasitic and infectious disease-causing organisms from new livestock BEFORE putting them in your system be a better idea than voodoo-izing after the fact?

"When in the course of pet-fish events..." you're sure to notice time to time reference to administering preventative or treatment "dips" and "baths". What are they? Used for what? How do you do them? What do you think I'm writing this for, geez!

A Dip? Is That Anything Like A Chaw?

No! Before you go sticking your fish twixt your gum and jowl, ala Red Man, read on! Ahem, how 'bout this for a formal definition: "Dips and extended Baths are a technique/process for (1) excluding undesirable organisms (& possibly chemicals), and (2) administering therapeutic agents (3) via a temporary immersion of livestock in a specially prepared solution". Beauty definition, eh? I just made it up. Some further explanation of the above key terms, mechanics and rationale, all right?

(1) Basically there are differential tolerances to certain semi-toxic chemical/physical environments between the "desirable" (one's we want) and "undesirable" (the opposite), hitchhiking critters and possibly chemicals that we want to include/exclude moving livestock from one system to another.

As part of this "greatest story ever told" most of this undesirable stuff is unicellular to at least not as resistant (slimy, thick, multi-cellular) as the desirables. Bacteria, Protozoans, "worms", necrotic tissue, crustaceans, and much more can be killed, impugned, sloughed off, at least reduced in number and virulence by the appropriate administration of preventative baths.

By citing "removing chemicals" as a function of these processes, I'm referring to two phenomena: A) Dilution of transport chemicals, & B.) Rinsing of surface material, e.g. fright pheromones, toxins in the example of puffer fishes, from the surfaces of the new introductions.

Are dip/bath routines really worthwhile for all the added stress, time and cost involved? Hello; well, yes...they are Standard Operating Procedures in all professional aquatic livestock collection, distribution and rearing facilities. If you have no other capacity for prophylactic quarantine, the least you should be doing are preventative dips. Is that clear?

What: Tools & Materials: Water:

"It's in the water", No duh. Oh yeah, oh heck yeah. Most all dip/bath regimens call out the specifics of how to make up the actual dip-liquid, including the base material: water.

1) It should be about the same temperature, when/if different, slightly warmer.

2) Physical phenomena should be about the same as the system the livestock is being put into. Only in the case of extreme stress will new arrivals be placed into a bath with conditions similar to their shipping water. Make sure you understand the absolute necessity of excluding ("mixed") "aged" transport water in the dip or new system. See below for reinforcement of this admonition under How To Do This Stuff.

I would pay attention to pH and temperature in trying to "match" shipping water, and blow off the rest of phenomena as relatively unimportant; and of course have adequate oxygen and no measurable ammonia or nitrite in the dip-mix.

3) When/where in doubt, use actual "fish tank" water as a starting fluid and add the active ingredients to "it".

A Dippy Materials Classification:

Various dip/bath chemicals can be ranked, ordered, otherwise described on the basis of their mode of action, activity, size/color/taste, whatever. Let's try a blitzkrieg approach:

1) Oxidizers: Oxidation Is Losing, Reduction Is Gaining or OILRIG is a useful acronym for detailing what happens in redox reactions. Losing and gaining what? Electrons! Anyway, re-dox is one way of describing a type of interaction between chemicals; their respective affinity for stealing or being stolen from in the way of their outer electrons. Many dip materials exhibit strong redox potential, in this case a tendency for losing electrons, or oxidation. A) Peroxides are the keystone example, with common hydrogen peroxide, H2O2, being the obvious most familiar and available example. This material is useful for supplying ready oxygen for emergencies, shipping solutions, is the reaction product of a few currently popular "stand-alone" in-tank filters/aerators, and dip/baths! In the advent of restriction of the familiar, but quite toxic formaldehyde solutions for sterilizing net dips, peroxides are finding a stronger and more frequent following. B) Another relatively popular oxidant is potassium permanganate KMnO3, check it out as a principal ingredient in commercial preparations as "pond" treatments for clarifying water and reducing algal growth, as well as a common treatment remedy for external parasites (epizootics). C) Copper Sulfate (CuSO4) is an even more common epizootic and algaecide, and is, among other things a considerable oxidizer.

2) Proteinaceous Precipitants: Basically, these materials elicit a mucus response, they make your livestock slimier. This is to some degree a good thing. Slimier is better than not slimy enough and definitely preferable to too slimy. Sliming off parasites and "glop" is a good idea, as is making sure the individual organisms have an adequate beneficial slime layer. See the references below for all the goodies these mucilaginous coatings do. They are eminently important for osmoregulation, excretion, respiration, disease control...they're vital. Too much or too little is a no-no, so presenting conditions like wiping them off by handling, or over-treating are to be avoided. A) Copper compounds mentioned above and B) Silver salts are in this category. Pay close attention to their use, especially if you are adding them to the treatment/quarantine system, not just dips. Use a reliable test kit, keeping the therapeutic dose as constant as practical. These materials are ubiquitous parts of a fishy medicine closet. Investigate those bottles you're using!

3) Insecticides: Like Dylox, aka Masoten, Dipterex, Neguvon, and more, and the still illegal, and it should be, Organo-phosphate Dimilin, are suggested by some as extended baths for cleansing of external parasites, in particular, copepods and "worms" on the bodies and gills of fishes. Like all Acetylcholinesterase inhibitors, these should be handled with care.

The former is still the treatment of choice for eliminating the intermediate forms of some freshwater and pond parasites, but are not suggested for marines (by me) at all. Dimilin is not licensed for use in the United States, and should not be used by anyone. The more you read and look around at the fish store's you will find products and endorsers of using these "economic poisons" as curatives for marine "diseases". I do not, repeat, not agree to the efficacy of their use, i.e. do not put insecticides in your system nor make them part of your dip/bath repertoire.

4) Formalin and formalin/malachite solutions are probably too dangerous and may well be disallowed by law in your area, they are in California. These cross-link peptides indiscriminately, destroying any and all proteins they come in contact with. In a very real sense, you're poisoning the "good guys" as well as the "bad". Hopefully the latter faster than the former.

Due to their narrow range of safety, toxicity to livestock and handler, and legal constraints, I would avoid formalin mixtures for pet-fish applications. Malachite green, zinc-free is no longer even used at most government labs and fish hatcheries.

5) Antimicrobials: Antibiotics as a rule are extremely limited in efficacy as dip/bath materials. One exception to this exclusion is the antimicrobials variously designated "Furacyn" compounds. Nifurpirinol (Furanace), Nitrofurazone and others I've found to be effective general petecchia (bloodiness), and what appears to be "Vibrio" in marine organisms....

6) Miscellaneous, my favorite category, inorganic acids, bases, salts, eye of newt, tail of frog, oh sorry, wrong spiel. Actually a whole-lot of hocus pocus that I can't seem to find substantiation for in what passes as legitimate (scientific, or at least testable, falsifiable, replicable trials) sources. And, tah dah(!), finally, the subject of this ever-too-long essay, the kinder, gentler dip:

7) Methylene blue and fresh water! What? Disappointed? Hear me out, this stuff works! And it's very safe. Methylene blue and fresh water is useful for both marine fishes and many invertebrates, a help against ich, skin and gill flukes, funguses, velvet (Amyloodinium) and most other external parasitic and infectious diseases. It has several other added benefits. It's a good oxygenating dye, sort of like our blood's hemoglobin, aiding in keeping oxygen concentration high. It also is helpful in reducing light penetration, soothing frightened livestock. In fact, Methylene Blue converts methemoglobin to useful hemoglobin, reversing the ill-effects of nitrite and even cyanide exposure.

These qualities are what make Methylene blue particularly useful as an "anti-fungal" for transporting stock and rearing eggs. Add to this the low cost, ready availability and lack of restriction on it's use and disposal and we have a winner! Score!

Should you have an impecunious situation, or are just a cheapskate (an inexpensive ray?), rather than buying Methylene blue solutions pre-made you can "make your own". Stock solid Methylene blue can be purchased from chemical supply outlets. Check your local "yellow pages". About one gram of dry material can be dissolved in about one hundred milliliters of water and about ten mils of this solution used per approximately one gallon of dip. Actual, keenly accurate measures aren't necessary as this material is safe and effective over a wide range of concentrations.

Okay, I'm Sold, How Do You Do This Stuff?

Here's what you need: 1) the intended livestock, 2) an adequate net and 3) bucket (no toxic chemical residues) or two, sufficiently large for the use at hand but not enough to allow the stock to thrash about in, and 4) dip material! Here goes:

1) Make up the dip mix. Use new or system water, adjusted/conditioned as prescribed.

2) Net, lift out the stock and place it/them in the prepared dip.

Thou Shalt Not Mix the Shipping Water in With The Dip Mix! Consider this just another (XI?) Commandment (no blaspheming intended). In fact, some fastidious types rinse the intended before the dip and after, before placing them in their next "home".

3) Watch Your Stock! What's that, number XII? No, I'm serious, unless you've done this a bunch or are using the suggested mellow Methylene blue, stay right there during the process. Your new acquisitions might just hop out onto the floor, you never know. Actually, the only reasonable way to gauge how much may be too much time to spend in the dip is to examine the dipped's behavior. If it becomes erratic (should I offer a definition? Nah!) with thrashing about, inversion, wild attempts at missile-impersonation, time's up.

4) Either rinse in an intermediate system-water only dip, or just net/lift the stock and place in the next quarantine/treatment or permanent system.

5) For long-duration baths, multiple-use of the same, OR the use of RO/DI water it is necessary to add a mechanical aerator (science jargon for bubbling airstone... pump, tubing...).


Nuff said, eh? As far as treatment modes go, in particular prevention of passing external pathogens from one place to another, dips/baths, especially in concert with quarantine periods, are the method of choice for optimizing results.

Methylene blue and freshwater is a most useful, inexpensive, safe and effective dip material for most all dip-able marine organisms. It is virtually non-toxic to even scale-less fishes and other sensitive groups when used as a dip.

As regards other "medicants", whether in a separate treatment facility or an established community, orally (food) administered medications are your best bet (other than environmental control) for most-commonly encountered complaints.

References/Further Reading:

Feist, Richard E. 1976. Administration of antibiotics and other remedies in treatment of fish diseases. TFH 1/76.

Fenner, Bob and Candy Fenner, D.V.M. 1986. Function of Body Slimes in Fishes. FAMA 6/86.

Gargas, Joe. 1993. Permanganate 1: The oxidant. The Pet Dealer 5/93.

Herwig, Nelson. 1979. Handbook of Drugs and Chemicals Used in the Treatment of Fish Disease, A Manual of Fish Pharmacology and Materia Medica. Thomas Publisher, Illinois.


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