One more to the party?

[Evan West]

So I know this is likely a no from what i know of stocking however, im consulting the gurus to make sure. I currently have a 20g long display with a sump that holds at least another 10g for a total system volume of around 30g. The tank is way over filtered with the fuge and skimmer. At any rate its a mixed reef with one clown fish, one starry blennie, one cherub angelfish, and one royal gramma. I had the idea of adding a cardinal fish? Guessing im fully stocked and this is not a great idea.

 

[Crabs McJones]

With that angel, I wouldn't suggest it. You're most likely maxed out already

 

[Darryl]

Get a bigger tank !
your already overstocked

 

[eatbreakfast]

What kind of cardinal were you thinking of adding? A deep bodied species, such as pj or bangaii likely wouldn't be tolerated well by the angel. However, a smaller, torpedo shaped species, such as orange-lined or margarita, should work, if your filtration can handle it.