Plagued Cardinal Tetras

[Omega0397]

I recently bought 6 cardinal tetras and 6 asian rummy nose rasboras for a well established 29 gallon (110 litres). My tank was not overstocked, consisting of only a school of about 9 neons, two bristle nose plecos, 3 small whiptail catfish and about 3 cory catfish. I have two hang on the tank filters, both of which include significant biological filtration material and I do 1/3 water changes every 2 weeks.

To start, everyone looked nice and healthy, then the cardinals within about a week starting dying off regularly until they were all gone. Once they had really started dying off, the neons i have had in there for 6-12 months started to follow suit, and now for the final act, the asian rummy nose have followed. The strange part is that the tetras never looked sick until right before they were about to die, and then they would be gasping and unable to swim. One of the asian rummynose did show some signs, it had a large white patch on its skin that suddenly appearred, and it seemed more like a discoloration of the scales more than as something growing on the surface of the fish. Regardless, it didn't last 24 hours after I saw that.

What I'm trying to figure out is what exactly these fish were getting sick and dying from! None of the fish appeared stressed with clamped fins or other outward signs. I have kept fish for many years and there always seems to be some sign that a fish is sick. The only thing I can possibly think of is that maybe there were some internal parasites involved? I keep thinking though that if that was the case the bottom feeders that go after the bodies would have been dying off with the others. Any thoughts or ideas on this would be helpful.

Thanks.

 

[lljdma06]

I'm no disease expert, as I've only had to deal with ich, fungus, and bacterial infections. The discoloration was curious to me. Neon tetra disease, though I don't know, please do not quote me on that. Could be also an internal parasite? Did you quaranteen the cardinals before you added them? Were they wild-caught, or captive bred?

I would post this in emergencies as well and see what results you get. How are the other fish? I would, for now, up the waterchanges.

llj

 

[Omega0397]

I had initially thought the same thing you did with the neon tetra disease (think its protozoan) and did some reading about it. Cardinals are supposed to be immune or highly resistant to neon tetra disease, so I'm not sure why they would have died off first, plus they exhibited no outward signs of unhealth. Unfortunately I don't have the space to have a quarantine tank (small apartment) so I just try to buy healthy looking fish and deal with anything that crops up, usually not an issue or at least one I can't handle. I will take your advice about the water changes and see if that helps anything. Thanks for the reply.

 

[Teephphah]

I went through a spell like this not too long ago. My best non-educated guess was Neon Tetra Disease, especially in light of the fact that it first appeared in my tank in the school of neons I was trying to build. (And it struck quickly in my tank just like in yours.) It killed indiscriminately for a while and now it seems to have run its course . . . knock on wood.

Like you though, I had heard that Cardinals were supposed to be resistant to NTD, which, is actually why I clicked on this post in the first place. I don't want to get burned again with the neons getting wiped out, so I thought I'd try cardinals. . .

Now I don't know what to do.

 

[drobbyb]

Just a shot in the dark here, but did you test your water when all this started happening?