Welcome to TRT!
One would suffice but you should be aware of a couple of things... firstly, clowns don't NEED an anemone to mate or "be happy"... and you should have intense lighting and a "safe" environment - no exposed intakes etc. because anemones can wander about and get sucked into trouble and pureed... not fun.
Another thing is, Rose Anemones are not their natural host - sometimes they will take to one, sometimes not - and you won't know until you try but don't be surprised if they don't go to it. Last week in the shop I put 4 true percs in my system with 2 rose BTAs and a green one - and 2 of the percs have decided to "host" in a little piece of PVC pipe that was being used to prop up a coral -- coral sold, I left the pvc in there and they have decided to call it home... rather like kids getting a toy in a big box and they cast the toy aside and play with the box instead
HTH
Jenn
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Member of the "J" Crowd & the BRW Crowd!
LFS Owner:
Imagine Ocean

Just keep skimming, just keep skimming, just keep skimming, skimming skimming! What do we do? We skim, skim, skim!