Corys going thru cycle

After my new tank cycled, I added 3 Corys a week and a half ago. I started testing my water after a couple days and nitrite was appearing around 1ppm. So I started doing 20% water changes daily. This wasn’t enough as one of my corys died. I saw him breathing heavy and wasn’t looking good.

I must be going through a mini cycle. I thought I completed the fishless cycle bc I was testing my water for a couple months. Adding ammonia, nitrites appeared after a while, then nitrate appeared with 0 ammonia & nitrites. Maybe I didn’t give the bacteria enough time to grow after the cycle and I messed it up?

The other 2 are still alive 2 days after the 1 died but they are not moving around much. Their gills aren’t moving rapidly like the one who died so maybe they are fine? I did a 75% water change after the one Cory died and nitrites were down to .25ppm. I guess I just need time to get nitrates to appear again to complete the cycle again?

I know corys prefer to be in a group of at least 3 but since I’m still cycling would it be better to wait on adding more? I feel like this is a tough decision to make bc I don’t want to mess up the bio load and throw off the cycle but I want them to be happy.

Any help on this is much appreaciated!

 

You are basically doing a fish-in cycle now. I’d just keep up with the large water changes to keep ammonia and nitrites at a minimum and treat the water with prime if you have it.

 

I do have prime for every water change. As far as adding more, would you agree to wait until the cycle finishes?

 

I do have prime for every water change. As far as adding more, would you agree to wait until the cycle finishes?

I agree, personally I would wait until your parameters are stable and your cycle is fully complete.

 

Well long story short, I completed a fishless cycle few weeks back then decided I wanted sand substrate. So I removed all my gravel and replaced it with sand (stupid I know). I bought 3 corys and as I was testing the water for the first few days I was getting high nitrite readings. I knew I messed up the bacteria colony and sure enough one of my corys died. I did a 75% water change a few days ago and my nitrites went down to 0ppm. Now it looks like I’m starting all over with the cycle. My current readings are .25ppm Ammonia, 0ppm Nitrite and 0ppm Nitrate.

Should I return my 2 corys and start the fishless cycle again? I can get it going with my ammonia source but I don’t think I want to do that to the corys in the tank. If I leave them in for a fish-in cycle, I feel like this could take forever.

Thoughts?

 

Cory Cats aren't very tolerant to sub par water parameters & probably wouldn't survive a fish in cycle. Be a good idea to rehome them during the cycling process.

 

Thanks for your reply

 

Your beneficial bacteria live everywhere in the tank, yes, HOWEVER, the majority live in the filter media so as long as you didnt remove that, your "cycle" is fine. Removing substrate and changing to another is not a problem.

That said, cycling with live fish isnt beneficial to the fish at all, its much slower, MUCH more work and especially with delicate fish like Corys.

 

I would like to think that my cycle is fine but I when I had a nitrite spike with no nitrates for days that makes me think I’m not cycled. What are your thoughts on that?

 

Easiest way to tell: How did you originally cycle the tank? I see you said you completed a fishless cycle a few weeks ago, but HOW did you cycle it? Did you dose 2-4ppm pure ammonia daily for 6 weeks while watching ammonia, nitrites and nitrate levels? Did you add filter media from an established tank? If you didnt do those things, you didnt cycle the tank originally.

 

It appears you got a double whammy. The only food the bacteria got while fishless cycling was liquid ammonia. I try to remember to advise folks to also add a bit of fish food along with the liquid ammonia. This thread will explain why i recommend doing so. PSA: Something I am seeing more and more often, fishless cycling.... | Aquarium Nitrogen Cycle Forum | 477380 In my humble opinion we grow a stronger colony of bacteria by giving it some of the kind of food it is going to get once fish are added to the tank.

The second problem is once the cycle appeared to be done it got disrupted by removing some bacteria by removing the gravel. Bacteria is growing on everything in our tank including the substrate. Doing so in a well established tank shouldn't cause a big problem but removing that much bacteria in a newly cycled tank caused what you are seeing right now. I recommend we give our tanks at least 6 months to get firmly established before making any drastic changes.

The original bacteria is still there. It is just going to take time for it to replace what was lost during the substrate change. Should you choose to keep the remaining corys you need to keep on top of the water changes to keep both ammonia and nitrites as low as possible.

BTW: 2 little corys are not producing enough ammonia to produce many nitrates. Between the big water changes and the low bio-load the nitrates are not going to go very high. Instead of rehoming the corys you may want to wait until the ammonia zeros out and then start gradually stocking this tank.

 

Well long story short, I completed a fishless cycle few weeks back then decided I wanted sand substrate. So I removed all my gravel and replaced it with sand (stupid I know). I bought 3 corys and as I was testing the water for the first few days I was getting high nitrite readings. I knew I messed up the bacteria colony and sure enough one of my corys died. I did a 75% water change a few days ago and my nitrites went down to 0ppm. Now it looks like I’m starting all over with the cycle. My current readings are .25ppm Ammonia, 0ppm Nitrite and 0ppm Nitrate.

Should I return my 2 corys and start the fishless cycle again? I can get it going with my ammonia source but I don’t think I want to do that to the corys in the tank. If I leave them in for a fish-in cycle, I feel like this could take forever.

Thoughts?

Honestly, I don't really see a problem here. Yes you did a water change, but now nitrite is constantly reading zero so that's good.

Ammonia can be 'stuck' at 0.25ppm even in an established tank. If you have not done a water change since a few days ago, and ammonia has not risen above 0.25ppm then it's not a problem.

To clarify, I am not saying ammonia is not toxic. I am saying that a lot of people read 0.25ppm ammonia even when everything is absolutely fine. A lot of theories surrounding that - could be just a false positive reading, could be a super low amount of ammonia that is entirely safe but because of the resolution of the test kit reads as 0.25ppm instead of 0, could be amino acids or other similar compounds that contain an amine group.

Regardless, presuming your testing is done correctly, and presuming ammonia never rises above 0.25ppm and nitrite stays at zero, your tank is cycled for the two cories you still have.

Nitrate at 0 is odd, but eh. Apparently it's hard to have the nitrate test done correctly anyways, and if you have plants or algae growing (not presuming you have either, just stating a possibility), that'll take up nitrates.