So flukes or brook wouldn't show on the guppies? Again when I had the outbreak the guppies were the first actual residents of the tank to die and that's why I thought they'd make a good test, of the 5 I converted I've had one death and it was the smallest guppy that is to be expected, but putting the other 4 into a clear container and observing them still shows nothing, no white spots or erratic behavior. I'm intentionally stressing them in hopes of weakening their immune system, no heater, no real filtration just an air stone to keep the water oxygenated. Their water temp dropped 10+ degrees last night, so one would think if there's anything in the water it would've found them by now but I don't know for sure so still waiting... impatiently lol.
I don't know about Brooklynella, but flukes can be pretty specific as to their hosts. Guppies are cyprinids, flukes that infest those can infest guppies, but others, not so much.
This "canary in a coal mine" is a neat idea, but it has lots of issues. Here is a write-up I did on the topic. Personally, I won't rely on the method.
Using black mollies to screen an aquarium for Cryptocaryon
In recent years, a procedure has been promoted that uses marine-adapted freshwater mollies to screen for active
Cryptocaryon infections in marine aquariums. The thought is that freshwater black mollies that are naive to marine ectoparasites, will soon develop infections if that disease is present in a marine aquarium.
With mollies being stark black, white parasites will show up in sharp contrast, making their identification much easier. Mollies have also been suggested to be housed alongside sensitive fish (that cannot be easily medicated) to serve as a “canary in the coal mine” for active disease.
The basic process is to acquire a small group of freshwater black mollies and gradually acclimate them to seawater over a period of up to 5 days. They then are added to the previously fallow aquarium, or added to the quarantine tank, and then observed for at least two weeks to see if they develop ectoparasites. If they do, then a treatment needs to be instituted, or the fallow period extended.
As with many aquarium ideas, over-extrapolation can reduce the effectiveness of the original idea. The process is really only suited to screen for
Cryptocaryon.
Brooklynella may not even infect mollies.
Uronema and
Amyloodinium can survive salinities as low as 3 ppt so may already be present in “freshwater” mollies that have been raised in brackish fish ponds. Marine and freshwater fish have basically the same internal salinity. Therefore, untreatable internal diseases, such as viruses and Myxozoans could possibly be brought into an aquarium with the mollies.
There is also a risk for introducing euryhaline trematodes into an aquarium along with black mollies. Fish farmers, wholesalers and retail dealers all understand that mollies benefit from being housed in brackish water, and so they usually add salt to systems housing mollies in order to reduce mortality under crowded conditions. Euryhaline trematodes take advantage of this, the trouble is that some of these can survive marine conditions and then hyposalinity is ineffective as a treatment for them.
Finally, black mollies have been used by scientists to propagate
Cryptocaryon in laboratories
. However, these studies went no further and there is no scientific evidence to indicate this method is actually effective. It is based on a theory, but it needs to be better tested. If properly applied, this process may have some benefit in screening for
Cryptocaryon, but falls short for all other diseases.
Jay
