Harlequin Rasboras swimming tilted, cory acting off

[HarpyFishLover]

Tank size: 10 Gallon
pH: ~ 7.4
ammonia: 0
nitrite: ~1
nitrate: ~5
kH: can't remember
gH: ~300
tank temp: 78F

Fish Symptoms:
I noticed when I fed the fish tonight that my cory was acting weird. She was almost motionless - at first I thought she wasn't breathing. Her color was wrong... the top of her head was a little yellowish.

I went to go look at the tank again, and I noticed all my rasboras are swimming a little tilted. I know this is a bad thing from reading other things long ago about it, but I can't remember what it is. (Also, their color is a little faded, which I know is a sign of them being stressed.)


Volume and Frequency of water changes: 50% every Wednesday (I skipped today because I haven't been home. I noticed this when I fed them when I got home.)

Chemical Additives or Media in your tank: gravel, live plants, some plastic rocks, I've got a charcoal pad in my filter, and an air pump

Tank inhabitants: 4 harlequin rasboras, 1 cory, 2 monkey loaches

Recent additions to your tank (living or decoration): none

Exposure to chemicals: As far as I can think, none

Photo(s):

Yes, I know cories need to be kept in groups. I had two, I was planning on getting more, the second died, Dory is the remaining cory.

(Edited because I forgot to use the format.. whoopsie... also added a pic)

 

[Colin_T]

The first thing to do if the fish ever look odd/ unusual or start acting weird is a 75% water change and complete gravel clean, and clean the filter. Do the water change and gravel clean each day until the fish show physical symptoms or the problem is identified.

The Cory in the picture looks fine but if you can post a pic of the harlequins and maybe a short 20 second video it might give us more to go on.

 

[HarpyFishLover]

For whatever reason, the harlequins are swimming normally now. And the cory seems to be okay for now... I'm really not sure what's going on in that tank but I'll go back to daily water changes for a week or so.

If the harlequins ever do that again, I'll be sure to get a video.

 

[Byron]

I agree about the water changes. And for the future, do a 50% or more water change each and every week, regardless. Nothing is as important.

Your test numbers have an issue though...nitrite at 1 is serious. Nitrite must always be zero. If it really is (or was) at 1 ppm, the fish would be seriously impacted, likely permanently even if symptoms seem better.