HELP! My guppies are dying from unknown illness

Hello everyone,
I’ve noticed over the past two weeks I’ve had quite a few adult guppies pass away, I’ve tested there water levels and they’ve been normal (0 nitrite, 0 nitrate, and 0 ammonium) and have tried medicating the tank with API PIMAFIX, MELAFIX, and their general cure medication. I have also done 2 20% water changer (1 each week that I’ve had the issue). The only symptoms that I’ve noticed in the fish that have died was minor fin damage, shimmies, and clamped fins, and today I noticed that one of my female guppies has a very long stringy white poop (I’ve inserted a photos below). Any help as to what I should do to help save my tank from losing any more guppies would be very appreciated!


I also forgot to mention that the tank is cycled, and I have not added any new fish to the tank in the past 6 months.

 

Welcome to Fishlore and sorry for your Guppy issues.
The first thing coming to the forefront of my mind is that the tank does not seem to be cycled. If you can do a 20% waterchange with conditioned and temperature adjusted water daily to flush out whatever may be bad in the tank, that would be a good start. But if you can fill the emergency template, that will give us a bit additional derail regarding tank size and age, stocking, feeding and will most likely get you to the resolution of your problems a bit faster. Hang in there!!

 

Sounds like you've had your guppies for over 6 months. If you got them as adults from the fish store it could just be old age. Guppies aren't very long lived especially ones bred elsewhere, shipped to stores and then to your house. My oldest guppies are the ones born in my own tanks.

 

Welcome to Fishlore and sorry for your Guppy issues.
The first thing coming to the forefront of my mind is that the tank does not seem to be cycled. If you can do a 20% waterchange with conditioned and temperature adjusted water daily to flush out whatever may be bad in the tank, that would be a good start. But if you can fill the emergency template, that will give us a bit additional derail regarding tank size and age, stocking, feeding and will most likely get you to the resolution of your problems a bit faster. Hang in there!!

Tank
What is the water volume of the tank?
- 29 Gallons
How long has the tank been running?
- 1 year and 3 months
Does it have a filter?
- Yes
Does it have a heater?
- Yes
What is the water temperature?
- 78°F
What is the entire stocking of this tank? (Please list all fish and inverts.)
- Guppies only
Maintenance
How often do you change the water?
- Once every week (sometimes every two weeks)
How much of the water do you change?
- 20%
What do you use to treat your water?
- I do not use water conditioners because I use reverse osmosis water or distilled water and have never had issues with it messing up water levels.
Do you vacuum the substrate or just the water?
- I syphone the gravel every time I do a water change.
Parameters
Did you cycle your tank before adding fish?
- Yes
What do you use to test the water?
- API Freshwater Master Test Kit
What are your parameters?
Ammonia: 0 ppm
Nitrite: 0 ppm
Nitrate: 0 ppm
pH: 7

Feeding
How often do you feed your fish?
- Every other day
How much do you feed your fish?
- A pinch worth of food
What brand of food do you feed your fish?
- Hikari fancy guppy semi-floating pellets
Do you feed frozen?
- No
Do you feed freeze-dried foods?
- No

Illness & Symptoms
How long have you had these fish?
- ~ 1 year
How long ago did you first notice these symptoms?
- 2 weeks ago
In a few words, can you explain the symptoms?
- shimmies
- clamped fins
- white stringy poop
- one guppy that had recently died had a bloated stomach before for a few days before dying.
Have you started any treatment for the illness?
- Yes I completed API General cure treatment, but only complete 4 or 7 required days of API pimafix and melafix medication.
Was your fish physically ill or injured upon purchase?
- no
How has its behavior and appearance changed, if at all?
- Some of the guppies have had minimal fin damage before dying.
- Some spend a excessive amount of time in one spot of the gravel of top of the tank (shimmies) before dying.
Explain your emergency situation in detail.
- It started with the only symptoms of the sick fish beign shimmies and clamped fins, I have since had one male guppy develop and bloated stomach and pass away, and now have noticed one of my females has very white long poop. With multiple symptoms leading to one clear illness/issue I’m having a very difficult time fixing/curing them. I have lost 11 guppies and am desperately trying to not loose anymore!

Sounds like you've had your guppies for over 6 months. If you got them as adults from the fish store it could just be old age. Guppies aren't very long lived especially ones bred elsewhere, shipped to stores and then to your house. My oldest guppies are the ones born in my own tanks.

I’ve thought that this may be the case, but I’ve had 11 die in the past two week and although some may be from old age I feel like it would be a crazy timing for all of my oldest guppies to pass around the same time…

 

True probably not just old age, there's probably a parasite or something - but being older and weaker makes them more susceptible. I don't treat sick guppies anymore - I let the weak ones die off and only have the strong and healthy breed and pass on their genes. Seems to be working - my tank bred ones that make it to adulthood don't get sick when the fish store guppies I throw in the tank with them once in while keep on getting sick and dying off.