Bespoke aquarium, Regal Angel

Benefits of a freshwater dip or bath:

We are an aquarium installation and maintenance company and we care deeply about the success of our client’s tanks. As a result, we would never deliver livestock without a thorough in-house quarantine process ensuring that the fish we deliver are as healthy as can realistically be expected.


Conditioning fish prior to delivery many times require ridding them of various parasitic infestations which have the potential to fatally harm the fish along with the potential of spreading throughout the client’s system and harming other healthy livestock.


There are multiple ways of accomplishing this goal. In this article I will discuss what I consider to be the safest and most reliable method available, ‘The Freshwater Dip’ method.



As the name of the article implies you will be taking a saltwater fish and giving it a bath in freshwater. A very scary proposition for someone not used to doing this and not ever having seen this done before. But rest assured, and this is coming from someone who’s dipped many hundreds of fish, the risk is minimal. I’ll admit that for many years I could not bring myself to dip a newly acquired fish, straight from the bag, before settling into its new home. I was nervous that the fish was already stressed from its trip and would not take well to the additional stress of a freshwater bath. But once I got over my hesitation and started doing it and saw only positive results, I would never go back. So please don’t let fear stop you. Like me, you will get used to dipping and will see the difference in having healthier, cleaner fish introduced into their new environment.


The Science:


Here I will give a disclaimer, I am not a scientist nor even the son of a scientist… I am a hobbyist just like you. But the science is pretty simple. The fish are way stronger than the live parasites that they are hosting. The fish can easily handle the short time period that they are in that strange freshwater bath, but the smaller weaker parasite cannot. The parasite from stress, induced by the absorption of freshwater, will loosen its grip on the fish, fall off and die. Depending how bad the fish is infected, you might need to do this more than once but I would not recommend more than once per day and I usually don’t find myself doing it more than 3 or 4 times total.


How to Details:

Everything you’ll need is on the table in this pic. Dip bucket, air pump, heater, PH tester and marine buffer.


I would recommend using pure reverse osmosis water buffered to match the typical marine PH of around 8.0 – 8.2. Usually, a pinch of any marine buffer preparation will do the trick. The temperature of the water should also match the typical 78 degrees that most aquariums are kept at. If yours is higher or lower match that. A small heater will help you reach the desired temp. I always use an air-stone to help oxygenate the water in the bath and keep the fish stress level at a minimum. Use of a typical clean pail (saved only for the bath) or small tank, of three to five gallons should suffice

  • Procedure
    • When dipping a new fish first acclimate the fish to the water in the system that it will be going into after the bath and only then proceed with the dip. Very gently remove the fish from its tank or acclimation bag and then slowly let it loose in the fw bath. I say gently because the objective is to have as little stress as possible on the target fish.
    • When returning the fish to its home, again gentleness is the game, minimum stress is the goal. In very short order the fish will be swimming as if nothing out of the ordinary occurred.
  • Duration
    • The general rule is to keep the fish in the bath for 5 minutes. If the fish is weak to begin with start with a 3-minute dip and work your way up on future dips. I once had an emperor angel fish in a fw bath for 5 minutes and when I reached in to remove him for return to his tank, he surprised me by jumping into a nearby fresh water pond that was filled with soaking driftwood. It took about 10 additional minutes to remove the wood and catch the fish. Needless to say, this was probably my most successful dip, with the fish still alive and healthy many years later.


Best fish to dip:


For sure angel’s and tangs. They almost always have some parasites, even if not noticeable, on them and they are strong enough to handle the bath without any problem. I also like dipping butterfly fish including heniochus butterfly’s, that quite often have fluke parasites on them.

Bespoke fish tank, Purple Tang with Marine Ich
Fish with marine ich
Pail with floating dead fluke after a freshwater bath

I can’t overestimate how much our mortality rate here at the Aqua Creations has diminished since we started aggressively dipping newcomers and fish with even slight signs of a problem. I would even dip fish that are only showing signs of a bacterial infection, as many times when a fish is weakening from a disease, they become a target for parasites or vice a versa….


When not to dip:


When the fish is already far gone and swimming erratically or in a very weakened state, it probably won’t help to dip and the stress might even hurt it and speed up its demise. I would also hesitate to dip a very delicate “expert level only” fish as it may be too sensitive to handle the bath. I also do not dip smaller fish like fairy wrasses, anthias and cardinal’s. If “you do” and see benefits please let me know.


In conclusion:


Although far from the only tool in an aquarist’s arsenal of remedies and prevention the freshwater dip is one of the best, cheapest and easiest to implement. I have a hunch that the only reason you don’t see more writeup’s extolling its virtues is only due to the fear factor. 

So, my advice is, just do it and you will see for yourself just how great a bath can be, not just for us humans, but for our fishies too…