What to do with 30 gal tank

I recently acquired a new larger tank and it's livestock from my parents. I have a 30 gal tank w/ sump/refugium. I plan on adding my livestock to the newly acquired tank. I'm not sure what I should do with the 30 gal tank but would like to have a predator tank. I was not able to find a great deal of info specifically for predator tanks. My main questions are, what would be practical in a 30 gal tank since most predator fish are very large and is there anything special that I would need to purchase or do for a predator tank? Also, I wanted to know what corals (if any) and what predator fish would be able to be placed in the same tank. I don’t intend on having many corals in the tank but would like to have a few just to add some color.

Thanks.

 

U can make it a puffer tank. Kinda like Puffer chick's tanks

 

Mantis shrimp might be cool,or a snowflake moray.You would need a good fitting lid for the eel,they're very good escape artists.

 

you could keep the 30 how it is and use the larger tank for a predator tank