How many anemone can a 30 gallon hold ?

+1 Make sure everything is thriving before adding anything else to the tank

 

condy eat fish, that why I asked was it going to be a nemo and clowns tank or nemo only tank. If it’s a nemo only tank and the OP goes the condy route, then that’s all that can really be kept in the tank.

But one thing I have seen that kinder surprised me, was a Pyg. Angle in a tank with about 10 condy with no “seen” issues. When I asked the guy about it, he said the Angle has been in there for about 2 years. Granted that was about a year ago.:-/

 

Another bit of advise, if you do decide to go ahead with the anemone (after stabilizing the tank! and making sure it's established)... go for a little lighter bio load. Think of the anemone as though it's a fish. It's messy, it eats, it "poops" and definitely contributes to the bio load. Additionally, you will need significant lighting to keep an anemone as the vast majority are photosynthetic. I built a DIY LED set up for my Biocube 29. It contains 24? 3W Cree LEDs. It is BLINDING how bright it is for a small volume... but the anemones love it.

Also know that if a decent size anemone dies in your tank, it can nuke everything in the tank. I took measurements of the water any time my anemone flinched for the first couple months.

 

condy anemones come from the Atlantic not the Pacific. A BTA is a better starter choice if you want the anemone to host some clownfish.
Only get an anemone if you have proper condition's in the tank and have high quality equipment.