Hi everyone!

I'm new to this board, and to goldfish (though not fishkeeping in general) as of last night! The way my new fishy is acting is a little disconcerting to me, and I wanted to check in with the experts here and see what you think.

BACKGROUND: I found my new fishy, a 6" comet, on our local Craigslist website, having been kept in a bowl (shudder) for some time, and his owner had finally chosen to give him up. I absolutely can't stand fish being kept in bowls, and since I have a newly set up 15 gallon tank, I thought I'd grab him and try to improve his lot, before someone else got ideas about keeping him in that bowl...

NEW TANK SET UP:
- 15 gallons
- Filtered with an appropriately sized filter and JAMMED full of ammonia chips (zeolite media)
- Ammonia/Nitrite/Nitrate: 0/0/0 (uncycled at present, filtered only with zeolite)
- One air stone running
- I'm going to put an oversized (rated for a tank up to 60 gallons) filter on the tank once it's cleaned, and I'm going to cycle the filter eventually (monitoring for, and controlling ammonia all the while)
- Currently the tank has a double dose of Prime as my tap water has ammonia, and the tank was only recently set up (not enough time for the zeolite to remove all the ammonia)
- Bare bottomed tank with only one large decoration at the moment, as it was a rush job!

ACCLIMATION: I drip acclimated him to his new tank water, from his bowl water for 50 minutes, then floated him in the tank for an additional 10 mins to be sure that temperatures matched.

BEHAVIOR:
- Swims right-side up, able to maintain position in water column without struggle
- Color looks good? (he's silver, so I'm not sure how I'd recognize faded color)
- Fins seem relaxed, not clamped
- No noticeable lesions or fuzz on body, though a few scales are missing
- Gill covers lie nice and close to the body, respiration does not seem labored
- Spends periods of time (possibly over an hour at a time) hanging near the surface, sometimes pointing nearly straight upwards (like "tail standing") and occasionally gulping/"glub"-ing at the surface, though not frantically. He is able to right himself from this "tail stand" position easily.
- At other times in between these episodes of hanging near the surface, he will station himself at other positions in the water column (but never crashed on the bottom) and will hang there, "glub"-ing on and off for long periods
- He has shown curiosity and has cruised around the tank - he didn't show any physical distress that I could discern when he was added to the tank
- Overall, he isn't doing much, mostly remaining stationary at various points in the tank, lazily sweeping his pectoral fins

Sorry for the small novel - just wondering what you make of his behavior and how concerned I should be? Betta fish are my forte, so I'm not quite sure what to make of this little guy and his behavior yet, but want to make sure that he's healthy and happy. Any advice is so appreciated. Thanks so much!

PS: I'm going to take a video of him and try to upload it to YouTube right now...

15 gallons isn't nearly big enough for the fish, that's why he's hovering. You have a pretty big comet right there and he'd probably be a lot happier being in a 25 or even 30 gallon tank. Not to mention that your tank isn't cycled so there could be plenty of things bothering him at the moment aside from lack of oxygen (the gulping at the surface and hanging around there is a sure sign of oxygen deficiency in the water).
Have you tested the water yet? Ammonia, nitrite and nitrates are most important for the time being, and of course pH. Here's a link to a thread about cycling: (Link is not visible to guests. Please register to view.) and maintaining: (Link is not visible to guests. Please register to view.) your tank

He could be uncomfortable too in such a sterile environment, but I of course understand the rush! Had some fish in bare-bottom tanks myself during emergencies In any case, the most important part is monitoring the water and changing it regularly.
Water changes will also add new oxygen to the tank and it most likely will help with his gulping and hanging, so if all else fails, just do a 50% water change

Good call! Just keep that up, zeolite will keep him safe for the time being

It's a pretty obvious reason why there's not enough oxygen in the tank, one being that the fish is big and the tank is too small! The minimum size for each goldfish is 20 gallons, but I'm sure you realize that's a very small tank as well, so at least a 25 gal is my recommendation, especially for a fish this size! If he was about 2 inches when you got him, he probably would be alright there for a bit longer.

I think I said "uncycled", meaning that the environment is fairly unstable for the time being, even if you're filtering with zeolite. The temperature for example could also be fluctuating a lot in such a small tank, but I doubt that would make Karat gasp by the surface. High nitrogens in the tank may also contribute to that behavior (even if you tested).

He might be fairly damaged from living in the bowl earlier, fish get stunted very quickly. And a 6 inch fish must have spent a while in that bowl by the way! Their internal organs simply grow too fast and too big for the stunted body to accommodate, still I've heard of stunted goldfish living for 17 years, so he's still got a good chance!
However, maybe you should try removing the zeolite soon and just dealing with the cycling by changing water a few times a week? This would quickly create a little colony of healthy bacteria in your filter
How often are you changing the water in the tank? In something this small, it could be an idea to do it every 5-6 days or so, or according to the ammonia/nitrite levels And then at least 50% of the water.

I had my baby fantails and two orandas in a 10 gallon (while my 83 gal was standing upstairs on the floor without space to be set up), and I was changing water every three days, up to 70%. The nitrates still went up to 30 in that time :/ And two of the fish from that time died between a few months and a year after that ordeal, even if they were moved to the bigger tank! So stunting isn't to play with @_@-

In any case, just ask whenever you have questions and I wish you best of luck! It's always nice coming across someone that cares so much for their fish