Can a fish death cause a nitrite spike ?

[Rich T]

Yesterday I noticed one very poorly male guppy struggling to swim straight and sitting on the bottom of the tank. He obviously wasnt going to make it so euthenasia was the best option for him I think

He also had signs of fin rot but I have been unable to purchase any meds due to lfs being shut for stock checks and re-organisation

He was still "just" alive when I removed him so he didnt actually die in the tank.
One thing I did notice was that when I lay him on a paper towel the edges of his tail were red and the red soaked into the paper towel


When I last tested the water conditions 3 days ago readings were :
amonia 0ppm
nitrite 0ppm
nitrate 0ppm

Ive just tested again and now my results are as follows :

amonia 0ppm
nitrite 2ppm
nitrate 0ppm


Seems strange to me that after only 3 days the nitrate has gone up so much.
The only signs I have that somethings is worng is initial signs of fin rot on my remaining guppy but I will be getting treatment for him today

Tank is as in signature, temperature is 25~26 degrees. All other fish are doing fine except for one old age pensioner of a minnow who is a little lethargic nowadays.

Last water change was 3 days ago and 50% was changed as I do 50% every two weeks and 30% at other times


Thanks peeps

 

[Joviella]

It is a bit worrying that you have no nitrate at all.....all cycled tanks run with some nitrate in them. Fish deaths can sometimes cause a nitrite spike,but as you said.....your fish didn't actually die in the tank. Are your test kits 100%?

 

[Rich T]

I would assume they are ok, I have no reason to doubt the kits as theyve always proved accurate in the past. Its an aquarium Pharmaceuticals kit with the test solution in an air tight bottle.


Its a smallish tank with a large very leafy plant in one corner so maybe that has something to do with the low nitrate levels

The kit I have jumps from 0ppm to 5ppm then up to 100ppm on the comparison chart so maybe there are trace amounts in the water but it just doesnt register on the scale ??

 

[Link]

You could try a more accurate kit. Hagen test kits are quite good in my opinion.
If you had serious nitrite problems all the fish would suffer and not just one. I dont think one fish dying, even if it had remained in the tank, would cause nitrites to rise

When your lfs shop opens you might find it useful to stock up on a range of remedies. I would go for Protozin for parasites, Myxazin or Melafix for bacterial problems and Sterazin just in case

 

[Da_Oz]

It is a bit worrying that you have no nitrate at all.....all cycled tanks run with some nitrate in them. Fish deaths can sometimes cause a nitrite spike,but as you said.....your fish didn't actually die in the tank. Are your test kits 100%?

I have had my 55g set up for over a year now and do my test weekly. So far had one reading with nitrate showing up yet. I ran a very planted 125g tank for 7 years and never had any at all, ever not even during what most people call the cycling period. Some tanks don't have nitrates in them, casue something is always eating up all that gets into the water.


Rich T did you add any new fish lately. This can cause a spike. Or change the filter anyway. Or if you have live plants and your leaveing in the dieing leafs. Lots can cause it.

 

[Rich T]

No new fish added recently (2x guppies two weeks ago)
As soon as I spot a dead leaf I remove it, they break off and float to the surface which is useful

Filter hasnt changed except for today where I removed the carbon for fin rot treatment on the remaining guppy.