Abnormal behaviour?

[Miaa]

It's got two corys and a red tail black shark. At first one Cody always followed the other. Now one of them sits in the pyramid and doesn't move whilst the other swims madly up and down the glass and then noses through the sand.
I feed them pellets and the shark flakes.
Levels: ammonia .25
Ph 7.6
Nitrite 0
Nitrate 0
(cycling so testing water every day and doing frequent water changes)

The two corys are bronze corys and one of them has a really red face like its blushing(it's the one that hides in the pyramid) and the other doesn't have red at all not sure if that makes a diff.
Going to do another water change tonight to try bring ammonia lvls down

Any advice?

 

[TotallyCoral]

How big is your tank? And what exactly is your question? The cory cat behavior seems pretty normal to me actually. If you can afford more after your cycle, they'd really enjoy that. A whole school is amazing to watch and will most certainly help with "shyness" issues. Cories are actually relatively hardy, however nitrate poisoning is most common which can affect their barbels (which might answer your red face question).