Los figueroa son mis nuevos . ellos son muy amables y su hijo carlos es mi nuevo amigo.

The word that fills the blank could be:

- Los Figueroa son mis nuevos vecinos. Ellos son muy amables y su hijo Carlos es mi nuevo amigo.

Explanation:

The translation of the sentence is:

- The Figueroa are my new neighbors. They are very kind and their son Carlos is my new friend.

In fact, there are very few words that could fill in the blank for the following reasons:

On some occasions, when a family member has a baby, it is mentioned that he is a new family member, but when mentioning the surname as outsiders the idea is discarded, another possible option would have been "amigos", but it is rare that a whole family becomes friends with someone being "nuevos", so the only viable option is "vecinos."

they need to keep water moving over their gills so they seem to have active periods and restful periods instead of undergoing deep  sleep.  they sleep swim

explanation: