So I have Telescopic Veil tail Goldfish that measures in at 8 inches from tip of mouth to end of tail. I bought him when I was younger and basically had no idea he could grow like this so I put him in a 5 gallon aquarium. When he reached 4.5 inches he got to a point where he wouldn't even play in his tank anymore because there was not enough space, and this bothered me so I stole my moms credit card (with my fathers permission) when she wasn't home ran to the Pet store and carried home a 10 gallon with better filtration and some stuff to cycle the tank faster. He is two years old now, and despite that he still plays in his aquarium, having to do so many water changes to keep the nitrite down is getting brutal so I know it's time to upgrade to (hopefully) a final home.
I was wondering, what do you guys think is a good size home for him, and what is the minimum I should get? My dad's Jeep isn't very roomy so the most we can carry in the trunk is 40-50 gallon tank.
Oh and if you want some other info on him, he still seems pretty healthy. He loves to swim and splash the water. He likes to be hand-fed and his favorite foods are Omega 1 goldfish pellets, but occasionally as a treat I feed him small pieces of bread, orange, or spinach. Sometimes he will also come to the top of the tank and let me and my mom pet his head gently. I named him Black because he is so dark I can't see him in the night.