# Mystery Killer



## mijotter (Jul 26, 2011)

Greetings, I have an established 29g tank. It has been established for several months and recently my Zebra Danios keep getting picked off 1 by 1 with all other fish seemingly fine. They have been mysteriously dying about 1-2 weeks from each other 1 at a time. They show no signs or symptoms prior and they all go to the same spot in the tank (at the bottom behind the big bridge decor near the intake)and just hover there the entire time without eating until I find them in the intake. There are no signs of fin rot, ich, or pretty much anything else, and like I said all the other fish are swimming around happily. The tank is not over stocked as there are 12 fish equal in size to the danios in this tank. Perhaps they are just dying of old age? The Danios were the first fish in my tank almost 10 months ago. I have 7 live plants in it and was wondering if maybe oxygen and CO2 might be a culprit?


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## susankat (Nov 15, 2008)

Have you checked your parameters of ammonia, nitrites and whats your water change schedule like. 

I have had danios last 9 years before loosing them to old age so the problem lies elsewhere.


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## mijotter (Jul 26, 2011)

Oh sorry I forgot to post parameters, yes everything is where it should be. One common thing I have noticed is they tend to get a small curve in their body. Nothing to dramatic though.


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## navigator black (Jan 3, 2012)

You left out a HUGE chunk of info. What are the other fish, and when was the last new one added?


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## mijotter (Jul 26, 2011)

Other than the 4 Danios
4 Kerri Blues
2 Odessa Barbs
1 Male Betta

The Blues were the last fish to be added, 8.3.12


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## coralbandit (Jul 29, 2012)

the Odessa while being listed as peaceful and compatable with tetras and danios also should be kept in schools of 5 or more.If your kerris are small(they don't get reall big)I would add more odessa if you want to keep them ,as they have been known to become aggressive(I've always thought they were aggressive, but like you only had pair{bad keeper, poor research back then}).Other than that I,m at a loss.


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## navigator black (Jan 3, 2012)

I'm stumped. I thought maybe you had a 'bad character' in there, or a recently introduced pathogen. Odessas can be nippy, but the danios aren't looking nipped. 
A bent spine before death can be a few things . let's try my checklist when I get mysterious malfunctions like this. here's what I check:
a) are the gills redder?
b) Is there a coppery or rusty dusting along the spine, behind the head (the parasite Oddinium sp)?
c) are there any raised patches on the skin, or sores? (bacterial infections - Mycobacter)
d) are there any red streaks in the fins, or do the scales stand up pinecone-like (bacteria)
e) have I missed water changes or filter cleanings,
f) and, very important right now - what is the poop coming from the fish like? Is it stringy and white, or is it more or less the colour of the food? Are there transparent sections in what is hanging from the fish? Are there bright red points hanging from the anus of the fish? With this, you are looking for worms - easily teated tapeworm types (stringy poop) or deadly and expensive to treat Camallanus sp. (red protruding mini-worms).


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## mijotter (Jul 26, 2011)

Thank you for the swift replies. To address the concern about the Odessa Barbs, I've had them for 8 months now and they are very non aggressive but the most active in the tank. The male just chases around the female from time to time never nipping though. 

To the second I got out my mag glass to look at the Danio more closely earlier before your post and other than the slightly curved spine, nothing else seems wrong. However with your guidelines on what to SPECIFICALLY to look for I will do so tomorrow as it is bedtime now and report back.

Update: I did a 15% WC and rinsed the foam pad in the Aquaclear and he came out from being at the bottom and is now just hovering in the same spot about half way from the top and still won't eat...


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## navigator black (Jan 3, 2012)

I'm sitting with my strong morning coffee thinking about this one. A standard ectoparasite would hit the whole tank at once, though it might hit one species first. But this one dying every few days does sound like internal worms. I hate using meds without knowing what I'm aiming at, as they can do more harm than good, but I expect you will see stringy poop. You may need an anti parasite medication containing praziquantel.


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## Marci99205 (Dec 13, 2011)

could it be neon tetra disease?


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## navigator black (Jan 3, 2012)

That virus causes a discolouration on the skin of the fish, and that wasn't in the description.


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## Marci99205 (Dec 13, 2011)

In advanced NTD cases spine may become deformed or curved.


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## coralbandit (Jul 29, 2012)

curved spine is found in many other disease along with isolation(not schooling with others of its kind);dropsy,bloat,swim bladder issue ,tuberculosis(very,very rare in FW) internal disorders just to name a few.I did just read of similiar case involving danios that got accepted as genectic defect that followed that paticular fish due to constant inbreeding.As all fish followed same dimise one after another(totall of 8 all purchased together).


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