Years ago my son brought home a bluegill in a paper cup. We put in an aquarium and fed it worms and fish food until it got big enough to eat a dozen goldfish at a time. The tank would become golden from all the scales in the water and the bluegill was so distended it could hardly swim… happily!
The aquarium was on a cabinet where it could look out the door down the hall. Bluegill have excellent vision! If it saw someone it would get all wiggly. The Guinea pig on the table next to it would then start whistling until you came in and rewarded both of them! Yeah, they tag teamed you!