Is a fish in the octopus family?

Answer 1

no

Answer 2

Not really. While both are invertebrates, they aren’t directly related to each other.

Octopodes belong to the phylum Mollusca. Molluscs are animals such as all cephalopods (octopi, squids, the extinct ammonites), gastropods (slugs and snails), bivalves (clams, oysters), chitons, tusk shells and some more worm like groups (tho real worms aren’t molluscs).

Meanwhile, Spiders are arachnids, which are arthropods.