Carplady's 55 gal. goldfish aquarium
Hello,
Carp (goldfish or koi) remain small or get huge depending on what and how much that you feed them. So, their size in your tank depends on you, mostly. All carp have the potential to get very large, as earlier mentioned, they can get up to 2 ft. long in a lake or large pond.
Carp do not have a stomach in the sense that other fish do, it's more of a holding tank to the gut. They do not have stomach acid and so the break down of food happens in the gut, making it real easy to overfeed. They always feel hungry and never feel "full". So it is up to you as their "manager" to help them. When I start off on a young goldfish or koi, I feed them three times a day. I keep the food diversified and handy.
First of all, you must decide how large that you want them to be, I prefer large (12inch)and obese carp, with metallic looking scales and bright colors. Perhaps you want yours to stay small so that you can have many in a small space. If that is the idea, then you will want to feed your goldfish 1 or 2 times a week. However there should be some floating plants and snails to provide them with snacks. I, on the other hand provide plants and algae on the back wall, and two feedings a day, now that they are as large as I want them to be. The foods that I use are a floating pond food for carp (there are some that add color enhancing food) , some dried tubifex worms, and algae discs.
My carp know me and act like happy little puppies wanting to petted. I call "here kitty, kitty, kitty", and they come to be fed ( I also use that to bring them up for company to see). I have a 12 inch, obese koi male, a smokey-colored lionhead female, at 5in., a shubunkin (mixed colors, even a bluish hue), female, about 6 in. and a comet (male) that is bright red and white. Oops I forgot that I also threw the dragonfish in there too (sometimes he swims with them). They are in the fifty-five gallon aquarium. I do water changes, and use carb/ammo-sorb in my big outside filter. About one fourth of the tank is taken up with floating plants and there is a sandy and gravel bottom. Be aware that they have a tendency to move your gravel and sand or substrate around regularly, plants do not stay on the bottom for long, they get pulled up.
I hope you try carp for a nice aquarium at your house. They need no heater, they can take oxygen out of the air, they can survive a long time without food, and they tame up real easy. I have had "feederfish" goldfish that turned out to be exquisite.
I hope this helps you to decide or enlightens you a little about carp, from Carplady

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