Multiple Fish Deaths

[Alexp08]

I have  a 65 gal hex tank with approx 30 fish in it. Over the last week / week and a half ive had a fish die a day. This tank has been set up for about 9 months now. I do weekly 20% water changes. 
 
I did some tests with an api test kit.
Nitrate = 5.0 ppm
nitrite = 0 ppm
Ammonia = 0ppm
 
The fish that have died are a mix of old an newer fish some died after a week, some after a month and some ive had since the tank started. 
 
No signs of ich or any other infection.
 
Im not sure what to do.  

 

[Byron]

I don't generally enter disease threads because of my very limited knowledge (been fairly lucky) and this is an area where guessing at diagnosis can be very dangerous.  But as I have gone through this sort of issue twice a couple years ago, I will just mention that when all other possibles (temperature, nitrogen issues, toxic substance in the water, fish aggression) have been eliminated, what remains is probably some type of internal protozoan.
 
I'm assuming this began after the "new" fish were added, which was a week prior?  Presumably this was not happening prior?
 
Byron.

 

[Alexp08]

I mean i had a few die awhile ago but it was nothing like this, maybe one a month. If that. So i guess the short answer is yes. I bought barbs from the LFS. and 3 or the 4 died within 2 days. That was about 2-3 weeks ago. 

 

[Byron]

 

I mean i had a few die awhile ago but it was nothing like this, maybe one a month. If that. So i guess the short answer is yes. I bought barbs from the LFS. and 3 or the 4 died within 2 days. That was about 2-3 weeks ago. 

 
And ever since those new barbs died, your other fish have been dying one a day, correct?
 
If yes, it seems likely the barbs brought an internal protozoan.  These seem to be fairly common in commercially-raised fish now, meaning the fish that are being raised on farms as opposed to wild caught.  Treatment is best with food medicated with metronidazole.  You are in the US, so you could get this already made from a retailer online, Angels Plus; here's the link:
http/www.angelsplus.com/FlakeMedProto.htm
 
Or you can make your own.  Seachem has the drug metronidazole.  You mix some with flake food in a zip-lock bag.
 
Byron.

 

[Alexp08]

Much thanks! Ordered some food and increased the temp. Hope this works!

 

[WILDER]

Sorry for your losses.
 
I had the samething happen when I kept fish. That's why in the end I bought a isolation tank.
 
Do the fish show any symptoms before death?
 
Signs of internal parasites are-
Long stringy white waste, or clear mucas waste.
Worms sticking out of the anus.
Swollen anus, or enlarged anus.
Fish will look skinny, have a sunken in belly region, or look bloated.
Bent spine sometimes.
Fish will sometimes swim on it's side.
Spitting food out.

 

[Alexp08]

The only symptom ive noticed and just because you gave me a list to look for. Is quite a few of them seem bloated 

 

[WILDER]

Hows the fish doing?

 

[Alexp08]

Well yesterday was the first day i didnt have any die. i turned the heat up to 82 about 4 days ago. But today i had two die and i also got the medicine flakes. So i started that today. All together ive lost about 15 fish

 

[Byron]

If the medicated food will target the issue, it will take a few days to become noticeable, and additional fish will likely die, so be prepared.  Metronidazole is an antibiotic, and like all antibiotics (even those humans are given for certain bacterial issues) they have to build up to work.  It is also important to maintain the dose for the full treatment, again just as with human antibiotics.  The package will provide the period needed.  When I make my own, I have fed this food exclusively for no less than 10 days, and usually 2 to 3 weeks.  Feed nothing else during the period, as you want the fish digesting as much of the drug as possible, and as with most "new" foods, fish may not gobble it up if any of their normal food is being offered.
 
Byron. 

 

[Alexp08]

Im just hoping the all dont die. The package says 6 days plus 10 days of their immune booster. 

 

[Byron]

Im just hoping the all dont die. The package says 6 days plus 10 days of their immune booster. 

 
Follow their advice.  In my case, I made my own food from instructions from a microbiologist friend from online, and the strength of the prepared food you have may be very different from what I made as an amateur.  Anyway, I hope this resolves things for you.  It is no fun to watch one's tank of fish dying one by one and day by day, I've gone through this twice.

 

[Alexp08]

Its miserable. i have one other tank battling ich but im not to concerned about that. Turned the heat up and theyre doing alot better. If only all sicknesses were that easy