Guppies Are Dying


New Member
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About 2 weeks ago I bought 5 guppies (2 males and 3 females). They were put in my 10 gallon tank which already had 3 albino Cory cats. Tank was running already for 10 months which no issues previously. After one week of the guppies being in the tank I come one day to see one male dead. Belly was a bit bloated but I didn’t think much about it maybe it could have been stressed or sick. Then 3 days later 2nd male starts to have white stringy poop. I then realize there is probably a disease spreading. I add aquarium salt and do 50% water changes. 2 days later it dies. Females who had black sacs previously seem to have aborted the pregnancy as there black sacs disappear. 3 days later A female passes and there are red blood splotches on her body. I am now down to 2 females 1 of who has already started to produce stringy white poop. The Cory’s seem unaffected and are swimming and eating like normal. I am assuming that the guppies have a good chance of passing also. What should I do after this is all over just do a water change and add new fish later on? Do I restart the tank and how would I proceed with a sterilization process of tank, filter, sand and decorations or do I wait and keep treating water with salt and do water changes. And if these are parasites do they stay in the water and media or only on fish. I really have no idea on where to proceed after remaining guppies pass and how to deal with this tank.

Sorry for the long message and thank you for taking the time to read.


Well Known Member
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5 to 10 years
Hi! Im sorry to hear about your problems.

Could you post pictures of the sick or dead fish? For instance, the red blotches on the female?

Clear, stringy poop suggests internal parasites. If we could ID the parasite then medication should fix the problem easily.

In the future, I would recommend quarentining any new fish you get to prevent exposing current fish to any diseases they might carry.


Valued Member
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1 year
Where did you get them? Chain stores put them out same day. Most good LFS will quartile them for 2-4 days. If the tank was stable and only the new fish died, it is likely the source that’s the issue. Doesn’t sound like a chemistry piece.

Also, if you can’t set up a quarantine tank, try a salt water bath in a large pot over dosing the tank.
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