Cory Swimming At Middle/top

Hi, I have 4 panda corys in a 20G high with some fake plants and a big decoration with lots of nooks.

Today, I changed about 1/4 of the old gravel substrate for sand, and the tank right now is about 3/4 sand and 1/4 of a gravel hill. I also added a terra cotta cave.

When testing today, about 7 hours after changing substrate and adding the cave, I had 0.25 ammonia. I didn't really believe it, so I retested and it read 0 or very close to it.

I noticed one of my panda corys was swimming near the top very often, around half the time, along the walls/corner of the aquarium. It's just this one. The rest of them are either sitting on the bottom, or sniffing around for food. Is this normal behaviour for the cory to swim near the surface often (not going up for a breath of air, just swimming along the top half walls)? Did I mini-cycle because of the substrate change?

In the meantime, I did a 15% water change and some vacuuming.

Here's my readings for the past few days:

Temp around 72 f.
9/17: pH 7.2, and 0ppm, 5 ppm.
9/18: pH 7.6, and 0ppm, 5 ppm.
9/19: pH 7.6, and 0ppm, 5 ppm.
9/20: pH 7.6, and 0ppm, 5 ppm.
9/21: pH 7.6, and 0ppm, 10 ppm.
(substrate change 25%)
9/22: pH 7.2, ammonia 0.25 (first test)/ 0ppm (2nd test), nitrite 0ppm, nitrate 10ppm
(15% water change)

Thanks for your help!

 

I don't think you have anything to worry about, he will settle down. I have seen my Corys do the same thing at times.
But you might want to keep and eye on him just in case.

 

Hm, your good bacteria colony can settle in the gravel so it’s possible that there was an upset in the cycle when some of the gravel had been removed. It looks like something got converted from the little increase of nitrates in the readings provided.

As for the little Cory guy, it Sounds like what someone once described as “glass surfing” which can be considered a symptom of stress. If that is the case then he may have felt the effects of the slight imbalance, but now that it looks like it settled then hopefully he will recover. But as countryrain mentioned, he should be okay but keep an eye on him.

 

Hm, your good bacteria colony can settle in the gravel so it’s possible that there was an upset in the cycle when some of the gravel had been removed. It looks like something got converted from the little increase of nitrates in the readings provided.

As for the little Cory guy, it Sounds like what someone once described as “glass surfing” which can be considered a symptom of stress. If that is the case then he may have felt the effects of the slight imbalance, but now that it looks like it settled then hopefully he will recover. But as countryrain mentioned, he should be okay but keep an eye on him.

I tested today (about 12 hours after yesterday's test), and the test is still on the threshold of 0 and 0.25 ppm ammonia. Nitrite is still 0, and I didn't bother testing nitrate. Fish look fine as far as I can tell, they are hanging out on the bottom, the glass surfer is not going it as much now.

Should I continue with small water changes?

 

I tested today (about 12 hours after yesterday's test), and the test is still on the threshold of 0 and 0.25 ppm ammonia. Nitrite is still 0, and I didn't bother testing nitrate. Fish look fine as far as I can tell, they are hanging out on the bottom, the glass surfer is not going it as much now.

Should I continue with small water changes?

You can try adding a little tetra safe start to incrrase your beneficial bacteria.

 

I tested today (about 12 hours after yesterday's test), and the test is still on the threshold of 0 and 0.25 ppm ammonia. Nitrite is still 0, and I didn't bother testing nitrate. Fish look fine as far as I can tell, they are hanging out on the bottom, the glass surfer is not going it as much now.

Should I continue with small water changes?

Yes, I would personally advise small water changes (~20%) as you continue to monitor the parameters for continual spikes of ammonia and nitrite to keep the readings in check. I'm sure this goes without saying to be sure to add appropriate amount of water conditioner to the new water prior to adding back to the tank just to help reduce any other variables that may contribute to the upset in the tank's cycle.

 

I don't think you have anything to worry about, he will settle down. I have seen my Corys do the same thing at times.
But you might want to keep and eye on him just in case.

Got home today, and found a floater Not sure if it was the glass surfer though.

I checked water- 7.6 ph, 0 ammonia, 0 nitrites, and I didn't bother checking nitrates...
I just did a 20% water change.

The floater had no obvious cause for death (other than stress..?) Gills were slightly pink, but nothing unusual imo, eyes were clear. Could I have stressed it to death? I was doing some vacuuming the other day, and caused him to swim away really frantically.

I have another one in my tank which is glass surfing (might be the original), and is also sometimes frantically swimming when I look at it through the side of the tank.

What's going on!?