A) Freshwater dip
In freshwater the parasite drops off the skin of the fish very rapidly. However, if the fish are simply returned to the tank where the outbreak occurred then they will just become re-infected. For this treatment to be effective (like all the dip treatments discussed in this article) the fish should be kept in a quarantine tank and the main display tank kept fish free for 8 to 12 weeks. Once in the quarantine tank the treatment should be repeated on days 1, 2, 3, 5, 7 & 11 followed by 4 to 6 weeks of observation in a quarantine tank.
As these parasites breach the skin as they feed on the fish the skins integument is broken and the fish’s osmoregulatory potential is hugely reduced. This is exacerbated in freshwater so remember that a heavily infected fish could easily become physiologically stressed with this treatment method.
One of the most important things about a freshwater dip is that it will buy you some time to start another treatment or to set up a quarantine tank as even a very badly infected fish can lose most of its parasite in a few minutes and improve quite dramatically.
To carry out a freshwater dip:
- Take some freshwater (RO is best) and heat it up to the same temperature as the tank: I find the best thing is to float a plastic ice cream tub full of freshwater in the tank until the temperature equalises.
- Adjust the pH of the freshwater to match the tank using a commercial pH buffer.
- Catch the fish and pop it into the freshwater bath, watch the fish carefully and be prepared to remove it if it becomes very distressed. Normally 3 minutes in a freshwater bath will dislodge most parasites; this can be extended to five minutes. I would not leave the fish any longer than five minutes in a freshwater bath.
- Catch the fish and put it back into the tank. Do not pour the freshwater back in the tank as this may introduce the parasites back into the display tank.
NB A freshwater dip is a pretty stressful process and is not advisable for very delicate or very ill fish.
Hyposalinty is often quoted as a good and safe way for treating Brooklynella hostilis
and Uronema marinum
. Unfortunately there are no scientific papers backing this statement up and in the authors’ experience hyposalinity, like copper, is hugely overrated in the management of these parasite. So if you DON’T want to cure your outbreak of Brooklynella
then by all means use hyposalinity therapy.
For this parasite, this isn’t the drug of choice. There are a few reports where copper has been used successfully to treat these parasites, but many more reports where it has been ineffective. In my experience copper is not effective for treating these parasites. However, in a quarantine tank situation copper may help after a freshwater or formalin bath treatment in reducing the parasite load.
Cheap, cheerful and effective: sounds perfect, so what’s the catch? Well it’s toxic, carcinogenic and an irritant. It is, however, one of the best treatments for Brooklynella hostilis
and Uronema marinum
. It can be purchased readily from your chemist and some off-the-shelf cures contain it or a related chemical (paraformaldehyde or gluteraldehyde) so a read of the labels or data sheets of some products is essential if you want to use it.
The best way to use this chemical for Brooklynella hostilis
and Uronema marinum
is as a formalin dip followed by a long term formalin bath (see environmental treatments).
To use it as a short dip in seawater, make up a bath in seawater at 200 to 250ppm for 1 hour. The dip component of this treatment regime should be carried out on days 1, 2, 3, 5, 7 & 11 after each dip the fish should be returned to a quarantine tank to which formalin has been added (see below).
For the long term long term bath component of this treatment, add 25ppm of formalin to your quarantine tank (it’s toxic to some invertebrates and algae, including most coralline algae species, so cannot be used in a reef situation after 10 days.
Remember liquid formalin (which is how you will get it from the chemists) is 37 to 40% formaldehyde and you want 25ppm so you need to add 0.0625ml formalin per litre rather than 0.02ml to get the correct dose.
NB formalin dips are a very stressful process and are not advised for very delicate or very ill fish.
As this chemical is very toxic I would recommend that appropriate protective clothing is worn such as gloves and safety glasses and use it in a well ventilated place.
In my opinion, Acriflavin is one of the most under-used treatments available to marine fish keepers. It has a broad range of effect, being effective against protozoans, bacterial infections and external fungal diseases. It is as “reef safe” as any other “reef safe” treatment and is easily obtained. It can be bought in several formulations from the LFS but make sure it isn’t combined with malachite green or methylene blue which have toxicity issues in marine systems.
It is effective at a concentration of 6 ppm against many ciliates (Paperna, 1984) and this dose should be added to the aquarium on days 1, 2, 3, 5, 7, & 11. Your skimmer should be turned off and any activated charcoal removed. It dyes the water a greenish yellow colour which will change the light spectrum reaching your corals (if you decide to use it in a reef tank - personally I believe all medications are best kept out of a reef aquarium and used in a quarantine tank) and this colour is a bit of a pig to get rid of, but after treatment turning your skimmer back on and adding activated charcoal helps remove the coloration (as do water changes).
Flagyl (metronidazole) is by far the most effective drug available against these diseases. Indeed it is the only effective treatment for fish that are internally infected with Uronema marinum
, but it has to be administered in the diet. To treat with Flagyl (metronidazole), add 34mg/l (34mg/kg bodyweight is required if treating the internal disease) of the drug to the aquarium water to be treated. A single dose should be effective, but it can be repeated daily, if required, as the drug is well tolerated by most fish. It is a very reef safe drug having little impact on invertebrates BUT it will kill off all protozoans and anaerobic bacteria in the treated tank, so, like all medications that are used in a reef tank, it will have some undesired effects on the ecological stability of the tank.
Some general comments on using treatments in a reef tank
The following words of warning should be heeded before chemical treatment of a reef tank is attempted. (Source: Simon Garratt, posted on UltimateReef)
“Modern reef keeping methods have now moved way beyond the days when LR was considered a simple source of bacteria, and filtration. In modern systems the 'critter' population regularly feature as a major player in the functioning of the tank. As such, any treatment should consider the impact it will have on the tanks ecosystem. 'Reef safe' chemicals have often only been tested with the most commonly kept 'show' inverts. Many have not been tested nor claim to be safe with the multitude of background life that 'modern' reef keeping deems as beneficial, and form a substantial part of a modern reef eco-system, especially those containing sand beds etc. The use of 'chemicals' designed to kill parasites can have disastrous consequences in more diverse systems as they will kill off these beneficial animals as well as the parasite. As a rule of thumb keep chemicals out of the reef tank and carry out any treatments in a specialised quarantine tank. Whilst it’s perfectly acceptable and correct to deem the survival of the fish as a priority, it shouldn’t be at the detriment of the rest of the system, and certainly not to the degree it jeopardises the systems stability.”