Great Pic Shex!!!!
Yep, they don't tell you when you win those fish how to take care of them, but putting it in a 55 gallon was Awesome!!!! I Love to see that! My Daughter won a Shubunkin and we started with a 10 gallon until I joined this Forum and found out how Big they get and how much they Poo!! Just make sure you have enough Filtration... Most experts recommend 10x the tank size in gallon per hour circulation. For example: 55 gallon tank = pump circulation of 550 gallons per hour from the filters! Sounds like a lot, but very important due to the amount of Ammonia Goldfish Produce. Even in a well cycled tank you end up with Spiking Nitrates.
I just got a 75 gallon and added a Fluval 406 AND a Marineland Emperor 400 HOB.
As for the veggies... I am not an expert, but Goldfish do not have a stomach (they don't get Full), and a lot will just eat and eat and produce more and more waste that will create the need for more water changes and gravel vacuuming. Keep an eye on the gravel.
That all being said... You are doing a Wonderful Job and gave that Fair Fish a Fighting Chance at a Very Long Life!!! (10+ years!)
Sent from my iPad using Aquarium Advice