Fish dying - HELP!

tantalus1662

AC Members
Nov 5, 2006
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I set up my freshwater tank about three months ago. Once cycled I got four neon tetras. I've never had any problem with these and they are still going strong. It was some time before I got more fish due to a holiday but then I bought three metallic blue guppies. After 10 days one of these died, followed by another one a week later. Both looked as though they had been fin nipped and just before they died they were gasping. I left it for another couple of weeks and the tetras and remaining guppy were doing fine. I then bought two cory albino catfish about a week ago. One of these has always been active but other not so. This morning the not so active one is lying on his side and does not look long for this world. Still the neons and guppy look fine. The other catfish is still darting about. My water chemistry and temperature are fine. I'm at a loss as to what is causing my fish to die. Can anyone help?
 
What size tank do you have? What kind of filtration?

Do you use a water conditioner? What brand?

What are your exact ammonia, nitritr, nitrate and pH readings?
 
My tank is only small (approx 30 litres). I have under gravel filtration. My Ph is 7.2, Amm 0, Nitrite 0 and Nitrate 10. it has been stable at this since about week 6 after starting with no spikes at all. Temperature is around 24-25 degrees centigrade.

None of the fish show any obvious signs of disease.
 
Sorry forgot to answer your other question.

I use Nutrafin Water Conditioner and Organic Waste Eliminator everytime I do water change (every two weeks).
 
Weekly water changes? Gravel vacs? Using test strips or liquid test kit?
 
Water changes are usually every 7-10 days due to my shifts. I use liquid test kits. Do use gravel vac but don't use it actually on the gravel as was advised not to with under gravel filtration.
 
When you added the fish did you do daily testing?
It may have gone into a mini cycle adding fish.
So your water parameters may have been that prior to adding but werent after. You weren't clear when you did the testing.
How did you acclimate the guppies?
 
I always do daily tests for 7 days after adding new fish - all levels stayed the same with no spikes.

I put the guppies into the tank in their bag. I then added my aquarium water a bit at a time for an hour before putting the guppies into the tank. I do this with all new fish I get.
 
It has been my experience, that with an UGF, you MUST gravel vac frequently and deeply. I am one of the oldtimers who still use the UGF and have for 30 years. Most I have converted to RUGF.

On a tank that only has a UGF, the physical waste is not being removed by any other means but by the vac. Disturbing the gravel will not kill or remove the beneficial bacteria, they are attached to the substrate.

As for the Nutrafin Water Conditioner/Organic Waste Eliminator, I haven't used it but the waste eliminator part of it smacks of a snake oil. It may aid in breaking down waste, but how it does it isn't explained on their site. Not sure if it bonds the ammonia released so it doesn't show up on your tests.

There are other agents you can not test for that can be detrimental to your fish, another reason for the vac.

It is also my experience that neons are very fragile and sensitive to water quality. The lightest thing off can make them rollover with no warning.

I would switch to something that doesn't promote its self as a waste eliminator, just a water conditioner, like Prime. Gravel vac deeply at each water change. On that small of a tank, I'd do 20-25% changes every 5 days, especially with keeping tetras. The refill should be slow to allow for acclimation with them.
 
Thanks I will start to vac the gravel. I know what you're saying about neons but they're the only ones that seem to be surviving this mysterious onslaught with no negative effects whatsoever.
 
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