I am having a hard time diagnosing a weird problem that my guppies have in my tank and I'm hoping that someone more knowledgeable than me can help me diagnose what disease my fish have.
Basically one of the guppies has an extremely swollen stomach. No scales popping out, no behavioral problems.. it swims normally, eats well, plays in the bubbles and acts just like a normal guppy. However its belly has been swelling more and more very gradually over the last month and now it is quite large.. the male guppy looks like he's pregnant. I googled like crazy and the closest thing that I see on this is "Dropsy", which appears to be a generic term for a wide range of things.. more of a symptom rather than a disease. The thing is, my fish doesn't have any other symptoms that I can see and does not appear violently ill. He's been getting bigger for 2 months now and still acts healthy, but this CAN'T be normal. Unfortunately my other 5 fish now seem to all have very SLIGHTLY swollen bellies and I'm afraid that they are going to get worse. I have reason to believe that this illness is contagious and waterborne and that a guppy can live with this for months and months without dying or looking sick except for the bloating. I'll give you the background on my tank and what led to this outbreak so you can see why I believe these things.
I have a 29 gallon freshwater (no salt at all) tank and a 5 gallon QT tank. My 29 gallon only has 6 male guppies in it. I give it a 5 gallon a week water change with dechlorinated tap water. Ammonia & Nitrite are 0, Nitrate is 5ppm or maybe a little less (hard to read exactly). The tank has been running for about 10 weeks.
Here's the deal.. I cycled my 29g tank and the 5g QT tank just using fish food and some filter media from a friend's established tank (1.5 years running). It took about 2 weeks. At the end of the 2 weeks when there was no ammonia or nitrite, my friend gave me 2 male guppies who looked perfectly normal. I never saw her tank. The guppies seemed happy and after a week of no issues, I went to the pet store and bought 4 more and put them in my QT tank. To make sure the water would be similar, before I put the guppies in QT I drained all the water from my QT tank and replaced it with water from my 29g, which I thought was a good idea.
I left the 4 guppies in QT for 3 weeks to check for signs of disease. When they looked fine after 3 weeks, I went ahead and put them in my 29g, giving me 6 total. Well, as I was putting the guppies in I noticed that the belly on one of the original fish in the 29g that my friend gave me was VERY noticeably swollen... to my horror, when I looked closely at the little guys who had just come from QT, I found that one of them a fairly "fat" belly and that the other 3 had slightly distended bellies. This makes me think that they caught whatever the original fish had by me filling the QT tank up with tank water that the original 2 had been in for a week or perhaps from the original filter media.
Not wanting to jump to conclusions too soon, I waited. A couple weeks went by and I noticed their bellies kept getting bigger.. now the original fish I got from the friend is really huge but the other 5 are still just "fat" but slightly growing. One is fat enough now that I think he's crossing the line from looking "plump" to looking "stretched".
I got worried and went to my friend's house to look at her tank. Well, what I saw shocked me...it was a little dirty and overcrowded and there were like 10 guppies that had MONSTROUS stomachs. I'm talking like the size of a quarter (US) on a little tiny guppy. It seems obvious that this disease progresses slowly and the fish just keep getting a more and more swollen stomach. Some of these guys looked like they were literally about to explode...like a guppy who swallowed a golf ball or something.
Still the weird thing is these guppies are not acting strangely. They are swimming and frolicking and having no issues at all that I can see in her tank except the giant bellies.
If it was your normal dropsy, wouldn't they be having trouble swimming or dying or having popped out scales or something? Anything other than just swimming around having a grand old time doing what guppies do?
I put my most seriously swollen guppy into my QT tank and started treating him with Maracyn-Two per package directions to see if maybe it was a bacterial infection. It's been 3 days and there's been no change in his appearance, positive or negative but it may be too early to tell. I'd hoped the swelling would at least reduce a little bit. If this doesn't work, I'll do a 100% water change and try something else on him. I figure if I can find a treatment that works on him in the QT tank, I can then dose the whole tank to save the other, less advanced cases but I don't want to risk the whole population experimenting with different meds.
What do you guys think this might be????? I'm really hopeful someone has some suggestions or something. I hear parasites are rare in US aquarium fish, but maybe it's that? I figure after the full 5 day course of antibiotics if this doesn't work I'd maybe try fungus or parasite or maracyn-one but i really HATE to just take a wild guess. I want to help my fish even if they don't act like they need it because I'm worried about organ damage. I really have searched the net trying to figure this out and I just can't seem to find anything that matches my exact case.. all this "ooo dreaded dropsy stuff, your fish will be dead in 2 weeks" stuff, but nothing like what I (and my friend) seem to have.
Please please help if you can.
Thank you so much for your time and reading this long post.