Rainbow Shark in my Scrubber

So I have this 10G test tank in the garage for my scrubber testing.

Stock
1--Female Betta -- 2"
1 -- Tetra-- 2"
1 -- Cory Cat -- 1 1/2"
1 -- Rainbow Shark/Cat -- 2 1/2" - The bully that picks on the other fish and especially my Little Miss the Betta.
Although that rainbow shark sure did keep the algae out of the tank.. including cleaning off my scrubber. (I didn't realize they were algae house keepers.)

If you have never owned a Betta get a Female. She isn't as elaborate as the males but she sure is friendly. When I work on the tank she is right there making sure I do it right.

Any way to make it short the Bully is ripping some fins apart on her and the tetra. Um so I thought maybe the Big boys in the 220G would like to play with him..
They haven't had live food in a long time.

So into the 220G the Rainbow Shark went.... Last I saw was the 6" Oscar dart across the tank. OOp he's done. A lot of chasing going on and he disappeared. Didn't see him anywhere. Hmmm the big boy must have gotten him...

Well in the reflection of my scrubber on the glass I kept seeing red... What the... So I have a street/aquarium smart Rainbow Shark with all the food he need right in my scrubber. When I clean it and reach my hand in there he hides under the Light guard for the bubbler...... :)