75 Gallon Tank Sudden Nitrate Bloom. 3 Dead Tetras


I woke up to a dead Phantom Tetra. I was sad and somewhat puzzled but not overly concerned; sometimes fish die for no apparent reason. Came home to two more Phantom Tetras who were weak and unable to swim properly. I took the little guys out and put them in a hospital tank and tested my water. Nitrates around 40 ppm maybe a little higher.
I immediately did a 75% water change, treated with Amquel+ and then kicked myself hard.
I had a Ramshorn snail infestation in my 55 gal tank and after purchasing 5 assassin snails I thought I would help by grabbing a bunch of these guys and throwing them in the 75 gallon for the loaches. I must have added 40 snails over a 6 day period. I do believe that the addition of these snails in some way increased the bio-load or the amount of fish feces or something and caused a spike in the Nitrates. Nothing else has changed in the tank, no new fish, no new decorations, nothing. It was also weird that the same species were affected and only that species-the Phantom Tetra. I think those little guys must have been more susceptible to the spike in Nitrates.
So spent the evening doing another water change and I hope I don't wake up to more dead or dying fish.
It was a reminder to me that if my tank is doing well don't mess with it at all. I am not sure how the two little guys will do but I had to take them out of the tank because the Angels were bullying them and if they are to die I don't want undue suffering.


Sorry for your loss...I also get overly complacent with my tanks sometimes. My planted tank typically handles itself with nitrates well. But I trimmed away a lot of my Java moss and a few leaves on some java fern died. It was enough to raise the nitrate higher then usual. Struck me by surprise.

Hopefully your snail situation will work itself out. I do know when snails die they can really add a lot of ammonia to your tank which would cycle to your nitrates.



I was just going to basically mention the same points..... dead leaves and dead snails = higher nitrate.

On another note, your tetras might also be stressed due to an improper school number. Tetras of all species really appreciate at least 6-8 of their own species as buddies. It gives them security and comfort.
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Actually all my Tetras: Silver Tipped, Red-eyed, Phantom have always schooled together.

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