The sentence you wrote is almost correct, but it can be made clearer and grammatically better. Here is a corrected version:
"Show stinging sea anemones that house a happy family of clownfish."
Explanation:
- We use "that house" instead of "housing" to make it a complete sentence.
- The word "house" means to provide a home, which fits with sea anemones providing shelter to clownfish.
If you want to make it even more child-friendly, you could say:
"Look at the stinging sea anemones that have a happy family of clownfish living inside."