Shy Cardinal Tetra

20G with guppies, platy, swordtails, cardinal tetras.

I've lost a couple of guppies lately. No obvious sickness symptoms, they just got slow and eventually died.

Anyway, I have a school of 6 cardinal tetras who always swim together. Last night, one tetra hid behind the plants and basically sat still all night. I did two 25% water changes. After the first, ammonia came up .25. After the second, ammonia was 0, nitrite was 0, and nitrate was 5.0.

Today, all the tetras seem fine (it's hard to tell them apart, so I can't tell which tetra was ailing). Everyone seems happy and healthy.
Is there anything I should be worried about?

 

No, he was probably just doing what fish normally do

 

has the tank been cycled?

 

That's pretty normal. You might want to up the number off cardinals though. 6 is pretty low. Theyll be more comfortable in a larger school

 

Hello, have you researched into why you received a .25PPM ammonia reading ? Though this may not be the reason your one tetra was acting a bit off, it can lead to future issues with your current fish. Best of luck.