Ive seen baby giants eat an arrowana that was the almost the same size as he was. Tank mates possibly wont last long. He will get more interested in whole fish the bigger he gets, from what ive seen anyway
I currently have a pair of about young oscars, about 4 inches, a 8 inch golden arowana, a 6 inch bichir, a pleco, and the snakehead that is currently 6 inches. They are in a 100 gallon tank that is 4 feet long.
Well the unexpected just happened! Well I ran out of goldfish yesterday, and today I was just feeding some pellets. The snakehead took 2 of the sinking algae pellets for the pleco! What a surprise! I think he was able to see the goldfish from his tank, so when I removed the goldfish bowl, so he decided to try the pellets. I know that algae pellets don't have good nutrition for snakeheads, but its a start towards floating carni sticks. To keep my other fish safe, I plan on getting rid of my snakehead when it loses its juvenile colors, or earlier based on its behavior.
Snakeheads will eat anything that hits the water if hungry.
And no there really are not other compatable species , pleuro's beeing a Pack hubter is the most likley species to tolerate large tankmates but even then its risky.