Before Costia kicks everyone's
rear-ends, please read the following. There are a lot of Japanese style shows
going on, and the aftermath of several over the last twenty four months has
read the same: Fish are mixed, returned home, novices do not take precautions,
Costia kicks their butt so bad it looks like a "virus" until it's accurately
diagnosed and cleared.
The significance of Costia
Life was simple for a fish vet in the early nineties. Japanese fish were too expensive for the average hobbyist and their beautiful wiles had not been fully discovered. The usual pond-call involved a poor filtration system, high ammonia levels, a sagging pH and a case of "garden variety" Trichodina on some hardy domestic fish.
One would simply recommend a treatment of salt coupled with an upgrade to the filtration type and flow. A week later, all the fish are recovered. Doctor Johnson is a hero.
Now, partly because my exposure is more widespread and Japanese fish are so much more prevalent, the fish veterinarian sees much more challenging things.
Salt resistance has arisen in the following parasites:
Flukes - 20% of cases are completely resistant to salt treatments at any level. Most cases are cleared at zero-point-nine-percent but less than thirty percent still clear off at the old zero-point- three-percent standby level.
Trichodina - 20% of Trichodina cases do not clear at even zero-point-six-percent. There are rare cases where trichodina does not clear even at zero-point-nine-percent which is also stressful to the fish. Formalin or potassium permanganate are recommended.
Chilodonella and Ich have never been recorded as being salt resistant in the least bit.
Costia has shown some resistance and it is part of the reason for this article.
Some outbreaks of Costia have been known to be salt resistant for at least two years. I saw my first case of salt resistant Costia in late 1996 on some Japanese imports straight from Los Angeles California. The Costia resisted zero-point-nine-percent stiff salt solutions and finally required Formalin for clearance, which works extremely well.
Costia is responsible for a lot of the recent fish mortalities we've
seen after Japanese style shows.
There are several reasons for this, which I
wanted to discuss here.
It has unfolded in several scenarios that after shows, participants begin to lose fish, sometimes with ferocious rapidity. The hobbyist does a few biopsies and does not find an organism. Rumours of a virus begin to spread. Finally, a competent biopsy is taken and viewed under a powerful microscope and the Costia is discovered. Unfortunately, it is often too late for a bunch of fish, when the proper biopsy and microscopy is done.
Recently, a good friend of mine had some fish that were beginning to isolate. The fish developed reddish lesions on the skin, and face. Some white slime was attendant at these lesions. Biopsies were taken and nothing was found. I asked if he'd biopsied the specific lesions themselves, and indeed he had not, because he felt it might further traumatize damaged tissues. This was a logical concern, to be sure, but as I stated before. Costia can exist focally, in small patches that can be missed unless they are deliberately scraped.
Formalin is the best treatment for salt resistant Costia.
The general idea of this Formalin treatment is to apply fifty PPM Formalin (two millilitres (equivalent to cc) per ten gallons) to a tank with the filter bypassed. Increase circulation with a floom or with a spraybar. Run this level of Formalin for two hours and then execute a forty to fifty percent water change, with de-chlorinator. Repeat the treatment in 72 hours. Do this Formalin treatment for a total of three treatments and you can rid your system of Costia and Flukes.
There is an important, auxiliary treatment for Costia which I have found to be very effective at slowing down the infection. I have been using topical hydrogen peroxide 3% USP applied directly to the patches. Here's how that works:
This has been particularly effective in some of the Ranchu goldfish that I keep, where facial or body scarring might be highly undesirable. These fish are able to handle high levels of salt with aplomb, so I usually endeavour to treat the focal lesions with peroxide. Then I salt the system to zero-point-six-percent to-zero-point-nine-percent.
There are several important follow-up points to this article.
During and after your treatment of Costia with salt at zero-point-three-percent, it is imperative that you serially biopsy your specimens to make sure the numbers of Costial organisms are decreasing or are absent. If you're still seeing Costial organisms after 72 hours in zero-point-three-percent salt, some level of resistance can be assumed. At that point you should either increase the salt concentration to zero-point-six-percent to-zero-point-nine-percent or consider Formalin. You should not use Formalin at fifty PPM with the higher levels of salt. I have used zero-point-three-percent salt and left it in during Formalin treatments. This has caused no problems in cooler water with high circulatory rates. I caution you that stiff (zero-point-nine-percent) salt solutions coupled with Formalin might create an oxygen availability/transfer problem. All oxygen tension problems become more acute under conditions of warm water, e.g. water over eighty DGF
A theory exists that Costia may exist in the fishes' cloaca, using these sequestered surfaces as it might use any other extension of the surface of the fish. In the cloaca, the organisms may be protected from short-term treatments like Formalin, and this ability to inhabit the cloaca is proposed as one of the possible causes of unexplained recurrence of the disease. Currently, the time has not been available to biopsy the cloacas of infected fish nor to attempt or ascertain the safety of clearance of said pathogens by swabbing the vestibule with peroxide.
Do not let your fish out from under your effective treatment until all biopsies are negative for at least three days.
KEY POINTS OF THIS ARTICLE
Thank you for your time.
Doc Johnson