octopus in refugium?

[fennec fox]

are there any really cool refugium fish or inverts like maybe a dwarf octopus i can have in my 5 gallon refugium?

 

[saltyfilmfolks]

No. octapus are really intelligent escape artist. They generally require a specialized tank.

I'm personally not a fan of the sump fish. My sump is nasty. That's its job. I don't think fish like that but some inverts do. Brittle Stars as cool and interesting mine has dearth maul markings and gets around regularly. I've never kept a mantis shrimp.
Youd need sand. Big non reef safe cowrie snail. They get big.

 

[Wrasse]

If you're looking for something a little different a fighting conch, sand sifting starfish, or cucumber (these can be really cool and unique! Like the tiger tail for example) might be of interest to you. I'd probably skip the octopus idea for the reasons @saltyfilmfolks mentioned but I have no experience or knowledge of dwarf octopuses. Keep in mind the above creatures all have differing care requirements and a small 5 gallon sump is likely not going to keep them very happy unless there's an excessive amount of crud replenishing the food supply.

 

[themcnertney]

No Octopus, however a Green Mantis Shrimp would be sweet.