And for the Clarkii I have had 0 problems with her in my 20gallon.
You're never going to have a probably with a juvenile clownfish that grows in a small tank, until it outgrows. Clarkiis are actually really big species of clownfish full grown, it's alright in there now judging the volume ratio, but it will need an upgrade in upcoming years.
My original concern was the mixing of two different clownfish in the same tank, but if that's working out so far I don't see much of an issue there.
The only reason I put her in my 20 was from the suggestion of the owner of the store where I bought her from. Store has been up and a very reputable store in SoCal.
I've bought horseshoe crabs, sandsifting stars, twin spot gobies, and mantis shrimp reccommended to me from the owner of the most trusted LFS in pennsylvania... All three of the former are
guarateed to have eventual starvation in home aquaria. Sometimes they make it in public aquariums due to larger sized tanks.. but hardly ever for aquariums.
As for the mantis, they can't tell the obvious difference between G. chiragra, and O. scyllarus..
The #1 most important rule in this entire hobby, is don't always take the LFS's word. Money is the only word that come out of an LFS's mouth.
But anyway, like Nina said about the star, it's fine until it isn't.. and when it isn't, you're not exactly going to be able to prevent the foreseeable damage, it will just happen. Concerning getting a different species of star, you can order serpent starfish (honestly the only species of star that should be in a 20g, and that's pushing it) if your lfs doesn't carry them in.
eventually, it will grow big enough to go after your fish. perhaps see if your lfs can order something more peaceful and maybe trade this one back?
