# A string of mysterious tetra/cory deaths - but nothing else...



## Redshrimp2709 (Mar 21, 2016)

Hello hobbyists. I'm wondering if anyone has any unique insights into a series of unexplained (to me) deaths in my 90 gallon softwater tank, with the majority of its inhabitants being South American fish, both wild caught and farmed. Before you suspect it may be horrible fish farms in southeast Asia or South America, I've had my population of cardinals, embers, golden, serpae, and green neons, for more than three months. Most of the deaths have been from cardinals, who have been in my tank for more than 6 six months, some even well over a year. I have had two pygmy corydoras die as well, seemingly having swimming bladder issues for the several days before giving up on life. There are no other symptoms or signs of a viral, bacterial, or fungal infection. 

My water parameters have also been tested, with NO ammonia/ammonium, nitrite, and low to moderate nitrates. I have not tested for heavy metals, that would kill my Amano and cherry shrimps, but they are doing just fine. I also have a beautiful male German ram doing just fine as well. My CO2 canister just ran out, and so the pH fluctuated .3 points (from 6.2/6.4, to 6.6). I have kept a solid, slightly acidic pH for the past 3 years as I'm keeping tetras, loaches, and corys. 

The only other possibility is a natural death, except a lot of my fish over the past 3 years have lived only just past 1 year, with perhaps a few cardinals and black tetras (forgot to mention above) surviving to about the 2 year mark. Has anyone kept small, Amazonian or southeast Asian freshwater fish that live a full life span according to what I've read online (most sources indicate tetras live 2 - 5 years in well maintained aquariums)???


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## TomC (Apr 21, 2010)

Regarding tetra lifespan, I have 15 of an original school of 20 black neons, that were bought full grown in November of 2014. They are still doing well and look healthy.


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## Reckon (Jul 25, 2012)

Check carefully if you see little red worms poking out from their bums. Callamanus worms may be hard to identify.


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## aprilsaquarium (Aug 22, 2016)

Going up in ph especially gradually shouldn't do it. Going down is harder on them. Cories and tetras can live just fine at 7.0 especially most of the ones you get at stores are bred and kept at 7.0 in the farms . Stable parameters are better than fluctuating . Try adding a bit of equilibrium and see if thst helps. If you don't have enough hardness filters can't do the nitrogen cycle . 
Plants also benefit from more
Minerals and hardness .



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