Fish death despite corrections?

[my_little_tetra]

Hi,

I've had my aquarium set up for almost 12 months now. I cycled it and followed the parameters using an API test kit (the kind with the little test tubes and liquid reagents). Everything went great. Now all these months later, I had gotten lazy and stopped routine testing. (I have been doing monthly 30-50% water changes). I had a sudden die off of three of my cory cats and one of my columbian tetras and was noticing some algae growth too. I tested my parameters and found my ammonia and nitrites at 0, but my nitrates were 80. Too high! I immediately did a 50% water change. 24 hours later, my nitrates are down to 30, but now another one of my columbian tetras appears to be near death and I can't find one of the two remaining corys.

Did I lower the nitrate level too quickly? Are some fish still going to die due to previous toxic nitrate level exposure despite the correction?

Thanks in advance for any help/advice!

 

[Coyne]

I don't think you can remove nitrates too quickly. More likely its sick from the previous exposure. Hopefully they will start to recover now that the water is better.
Maybe up the PWCs to weekly or at least every other week to keep the nitrates in check.

 

[Fishanatic]

Hi,

I've had my aquarium set up for almost 12 months now. I cycled it and followed the parameters using an API test kit (the kind with the little test tubes and liquid reagents). Everything went great. Now all these months later, I had gotten lazy and stopped routine testing. (I have been doing monthly 30-50% water changes). I had a sudden die off of three of my cory cats and one of my columbian tetras and was noticing some algae growth too. I tested my parameters and found my ammonia and nitrites at 0, but my nitrates were 80. Too high! I immediately did a 50% water change. 24 hours later, my nitrates are down to 30, but now another one of my columbian tetras appears to be near death and I can't find one of the two remaining corys.

Did I lower the nitrate level too quickly? Are some fish still going to die due to previous toxic nitrate level exposure despite the correction?

Thanks in advance for any help/advice!

As said, its due to the previous exposure. Some fish might die, but you should start changing water more often. Imo, they are probably stressed right now, that's probably what killed them. Test you're ph also, it ca be a major factor.

 

[librarygirl]

Actually changing parameters too quickly can affect some fish, but IDK if a drop from 80 to 30 would be that significant. The nitrates show that you need to up your water changes though; 50% weekly with substrate vacuum is good practice. You also might want to swish your filter media in old tank water during the next water change as well.

 

[my_little_tetra]

Thank you for the replies!

I will definitely up the water changes and keep up with routine testing.

I did test my pH, but it hadn't changed at all so I didn't think it could be a problem. It's on the higher side, because my tap water is high. 8.2. But like I said it's been there since I originally set the tank up. No change.

Good news is, the cory I couldn't find reappeared and is happily doing his little catfish thing around the tank.

Not sure if the Colombian tetras are going to be so lucky. They aren't looking so good still.

I added a second cartridge to my filter. Its a Biowheel type Penguin 200B with the two media slots. Not sure that will help anything or just waste money, lol. I've been changing the filter cartridges monthly.