spotted cory getting pale

[corygirl50]

Hello I'm 3 mths into this so newbie fits me. Freshwater 16 gal tank, one female betta four spotted cories (love them all) three cories normal spotted. one named William Wallace named for the fly to the top and side to side making me think he's wants freedom... he's about 3/4 in and he's getting paler, he eats brine shrimp well swimming around the top to get at it. He swims stong up but he seems to go limp and float down. He seems to skim top, sides and foam filter most. He gettng paler, the others are all fine. Any suggestions or similar situations?

 

[Rbishop]

Tank readings from a good liquid test kit?

Could be just a poor genetic one if purchased all at the same time.

 

[corygirl50]

I have the API kit right now but have read some things that some say it's not the best...
PH 7.6
High PH 7.8
Ammonia .25
Nitrite .25
Nitrate 5.0
I'm still working at 0 ammonia. Didn't feed them yesterday.
Sometimes he acts sick then normal swimming he is a lot paler in the last two days.
25% water change tonight and watch him closely.
Thank you for your response.

 

[Rbishop]

I think your tank isn't fully cycled, possibly with a low quality fish in the mix. Up those water changes to 50%, even if daily to keep ammonia at zero.

 

[tanker]

And when you clean filter, use tank water to clean,

 

[corygirl50]

Thank you 50% change done earlier today and rinsed filter in tank water 0 ammonia right now, but will check again tomorrow. Grateful for suggestions. Cory doing right now still pale tho.