What happened to my guppy??

[fishwish34]

Okay...I had a male guppy (and many others before him). I got 2 female guppies to be friends with him, and soon after, he died. Symptoms were a slight hump in his back (behind his eyes, but before his fin), what looked like a little ridge of scales sticking up on top, and paler coloring. He disappeared...in this past week or so, I've noticed one of the female guppies has a slight hump in her back, and has stopped coming up for food. She hangs out on/near the bottom of the tank. Today, I did a water change and found her dead. What happened??
My tank is a 20G high, with 5 zebras danios and now just one guppy (female).
Before doing the water change today, I tested my water. The results were:
Ammonia-0
Nitrite-0
Nitrate-10 (there is a slight chance that this is wrong because I may have put an extra drop of test solution in)
pH-7.6 on pH test, between 7.4 and 7.8 on my high range pH test

I've had similar symptoms with pretty much all of the guppies I've owned. Now I just have the one guppy, and would get her friends...but I feel like then she will die Other people have mentioned that this could be fish tb, but wouldn't that affect ALL of the fish in my tank? Most of the zebra danios were bought before and have lived beyond the guppies that have died. Is there a disease that only affects guppies?
I'm not sure what to do at this point...thoughts?

 

[OrangeCones]

By your discription, it could be Fish TB, but the raised scales sound like dropsy.

Not all fish will catch a particular disease. If it is affecting only the guppies you have recently added, perhaps the source you are buying from has the disease and the fish show it when you get them home due to the stress of moving.

Are you keeping new fish in a quarantine tank?

 

[fishwish34]

No, I don't have a quarantine tank...I know I should, but I don't know where I would put it.

All of my guppies have died in a similar way, usually after being in my tank for a couple months. Most of them I have gotten from PetSmart, but the latest two females I bought somewhere else. Also, I haven't bought them all at the same PetSmart.

If it helps, the raised scales weren't all over. From what I've read, fish look like pinecones when they have dropsy. My guppy didn't look like that, there was just a little line of scales poking up a tiny bit on top. I think he was getting thin, too.

How would I treat Fish TB?

 

[OrangeCones]

You could search the Internet for information on treating fish TB. From what I understand, there is no cure.

 

[fishwish34]

Well, most sources on Google say that lesions on the fish's body would be another symptom, and I have not seen any of those on my dead fish.
A few sites suggest using an antibacterial, some say there is no real cure...and that the bacteria is very persistent. Some suggested bleaching the tank (without the fish in it, of course). One person said vitamin deficiency or a parasite could also cause a curved spine.
There were also several horror stories about humans getting fish tb from their tank. I really hope it's not tb. What should I do now?! I don't want to take apart the whole tank, either. All of the other fish look fine, it's only the guppies that die this way.
When I was at my lfs the owner there said that in the pet store trade they call guppies "annuals"--not in the killifish sense, but because they have short lifespans. They reproduce at such a ridiculous rate that it isn't necessary for them to live a while. Not sure if this is true or not...

 

[OrangeCones]

I'd kept guppies many years ago, many lived for several years. Livebearers are not 'annuals.'

I think that the problem with fish like guppies is that they have been inbred for so many years to produce the color/size of the their fins. This take a toll on the health of the fish.

Fish TB is not like human TB, so no worries about that. It CAN cause a skin rash in some. Wash your hands/arms if you do anything with the tank is the best advise my vet that used to work with zoo aquariums gives.