Got a question about tobacco hornworms?

-So i had a single tomato plant just to grow a few for lunch every now and then. It popped out some good tomatos but recently stopped making them and started dieing. While throwing it out today i found a giant worm. Really cool looking, turns out its a tobacco hornworm. I would say it was a tomato hornworm but its not dark green enough and the pattern and shape matches exactly to every picture of tobacco hornworms. Anyway he now live in a bucket i put him in with some fruit and the dieing tomato plant. I dont wanna kill him, any tips on raising him and making his home better?They like to swim around in the fish pond.