Corydoras not eating - 1 died

[ITsJake]

I cycled my fish tank over the last 2 months (fishless). Once it finished I bought 3 corydoras about a week ago. I noticed they haven’t been eating the shrimp pellets I’ve been giving them so I started testing my water and I started getting nitrite again (1ppm or less) with small amounts of nitrate. No ammonia. Not sure what is happening but I’ve been doing 20% water changes every other day to reduce the nitrite levels. Will my mini cycle be prolonged with these water changes? I want to make the fish comfortable. For the most part they are active and move around exploring. What should I do to make them eat more? Any advice would be greatly appreciated!

 

[georgelee1000]

If your tank is fully cycled, I won’t do daily water change. It will just stress out the fish even more. 3 is not a great school so they may feel timid. Try frozen bloodworm occasionally. Otherwise keep your regular routine. They should eat here and there if they are exploring.

 

[ITsJake]

It cycled however I’m thinking I didn’t give the nitrate colony enough time to establish and maybe that’s why I’m seeing nitrites? I only have a 37 gallon tank and want to add a variety of fish eventually so that’s why I went with 3

 

[georgelee1000]

What I mean is I don’t think it’s fully cycled. You should not see nitrite at all. Keep an eye on the water parameters and keep an eye on the fish.

 

[ITsJake]

I’ve been battling high nitrite levels by doing daily water changes. The first few days I bc was doing 20% but yesterday I started 50%. I use prime with every WC. I noticed one of the 3 corys was breathing extra heavy and when he went up for the normal gulp of air, he would float down and land on the center piece. Didn’t seem like he was doing well and I woke up to see that he died this morning. The other two aren’t very active at the moment buy hope they can pull through Should I continue with daily 50% water changes until nitrite is below .25ppm?

 

[DoubleDutch]

Yes a good idea I'd say.
How did nitrites get up?

 

[ITsJake]

I cycled by tank before adding fish but then I replaced the gravel for sand substrate and my readings started to show Nitrites again with little amount of Nitrate. So I am assuming I am going through a mini cycle since this has been going on for a week now?