So, there seems to be a mysterious wasting disease striking all of the guppies in North America. It might even be world wide I don't know but I do know it has affected all of the guppies I've seen in the last 5 years.
Here is what we have observed:
The guppies looked good - boys were chasing girls, eating, nibbling algae, producing babies and generally acting like guppies.
Suddenly there were no more snails. We considered it a blessing at the time but should have taken it as a warning. There are many reasons snails might die so I would not take dying snails to be a symptom but rather a warning that something is going wrong.
Then there seemed to be no more offspring.
Then the girls started to look skinny
Then the gravis spots disappeared. Some of our girls got quite nippy when the boys, who seemed to fare a little better, continued to chase them.
Then the "feces" became long stringy and white. (Leading to our family name for the problem as white stringy poo disease)
Then the girls started to die. Some of the girls skipped the white stringy poo and seemed to expand as if they were going to have a 100 babies at any time, though they had no gravis spots. They usually died within hours if that happened.
A few days after something started going wrong with the girls, the boys started to look damaged. Their tail fins got thin, and ragged as did the dorsal fins. Their colour faded, they stopped chasing the girls and they too eventually died.
I can honestly say it was 100% fatal. We lost over 200 guppies in 3 weeks, though, the full catastrophe took almost 2 months. We have guppies again and a lot more knowledge. Are you interested yet?
The cure:
The easiest fix is to euthanize all of your fish, sterilize your equipment and cease keeping guppies but that probably isn't what you want to hear.
So, the first thing you need to know is what you are dealing with. This is a protozoan and here is a link to a Wikipedia entry that will tell you all about your friends.
I stumbled upon this knowledge not by any special equipment or tests but by desperately trying every medication in the fish store and finally halting the spread of the disease. Every fish which displayed symptoms died. Those that did survive (roughly 10/400) never did have offspring again and were a sorry lot compared to my glorious red cobras. *sigh*
Secondly, you need to go find yourself some "hole-in-head" treatment. I used Jungle Labs hole-in-head guard but I do not think the brand is important since hole-in-head and white-stringy-poo are so closely related.
Now, you need to do dead scoop and, for the sake of the suffering fish, please put the really sick ones out of their misery. Even if the medication doesn't say to, do a 25% water change before your start and clean up your tank. Then follow the directions for the medication you bought. It may not dissolve in the tank very well so you may want to scoop a cup of tank water out to mix it in with.
Equipment hygiene. I know you have heard that before but everything that goes near your tank is going to need to be sterilized for as long as the treatment goes on.
I tried other things that may or may not have helped. The one thing I do think did some good was adding salt to the water at the rate of . This helps treat any secondary infections that may occur without adding addition medication. Once you have gotten rid of white-stringy-poo disease you can start worrying about some of the other things you have no doubt seen. Like red bushy poo disease.
I will tell you that you should say goodbye 90% of your fish if you observe this disease. It might be more successfully treated in larger fish but guppies are too small.
