Random nitrite spike

[Austinp42]

I just happened to check my tank in the middle of the night and noticed one of tangs were dead and a flasher wrasse I took them out of the tank immediately and tested my water and it showed my nitrite was at around a 2ppm but my ammonia was at a zero and have no clue why it’s like this. Luckily I have a 50 gallon also and was able to transfer the rest of my fish into that tank. Any suggestions on how this could have happened. My tank has been fully cycled for about 6 months

 

[Fish Fan]

Nitrite isn't toxic in marine aquaria, especially if your tank has been running for some time (many months)

I'd suspect testing error with the nitrite, and even if it was accurate, 2.00 ppm nitrite is far, far below the level you'd need to harm fish.

If your fish suddenly died you may have other issues and we'd be happy to try and work through those scenarios with you, but you can safely rule out nitrite poisoning; it doesn't happen in home aquaria

Good luck going forward!

 

[Austinp42]

Nitrite isn't toxic in marine aquaria, especially if your tank has been running for some time (many months)

I'd suspect testing error with the nitrite, and even if it was accurate, 2.00 ppm nitrite is far, far below the level you'd need to harm fish.

If your fish suddenly died you may have other issues and we'd be happy to try and work through those scenarios with you, but you can safely rule out nitrite poisoning; it doesn't happen in home aquaria

Good luck going forward!

I checked the fish that died and they didn’t have ick or velvet so I have no clue what’s going on

 

[Fish Fan]

I checked the fish that died and they didn’t have ick or velvet so I have no clue what’s going on

I'm sorry you're having some difficulties, but nitrite didn't do it, I promise

It's difficult to see any parasites on a dead fish, but true marine velvet is rare. Ich is much more common.

Could you tell us more, like how long you've had your Tang and did you add any other livestock recently?

 

[EnterName]

Just double checked. Assuming it isn't a testing error: 2ppm NO2 came from less than 1ppm total ammonia. To low to kill multiple fish within a few hours and if the 0ppm reading is correct the initial and important part of the nitrification is still working properly.

As Fish Fan rightfully said: nitrite is not dangerous in reasonably achievable levels in reef tanks.

Do you have any coral? How do they look? If something is wrong with the water they should show signs of distress. It's not a perfect indicator but a good litmus test without having to go through all parameters in detail.