Goldfish Sudden Death?

Hey all, was wondering if anyone had any ideas on why my goldfish might be dropping off one-by-one lately.. I started out with a 15 gal tank a little more than a year ago, I added 10 feeder fish and of those 10, only 2 survived, but they continued to live throughout the year and more than doubled in size. For Christmas this year I got a new 50 gal tank and got it all set up; clean new gravel (thouroughly washed), used the same live plants from the original tank, same decor, I even used the original water so it would mix in with the fresh water and cycle better. I added PondStart (for stress and slime coat) as well as some dechlor. I let the tank cycle a day, and put my fish in bags so that the temp would adjust before adding them directly to the water. For over a week they both did great, and all of a sudden, I awoke one morning to find the biggest of the 2 to be dead?? No prior signs of weakness or health, and he was eating fine. It was all of a sudden over night with no explanation! I felt bad that my other goldfish was alone in 50 gal so I added 2 from one of my ponds (another feeder and one Commet) The 3 did great together for more than a week, so I purchased 3 Ryukin to accompany them. When I added the Ryukin, they adjusted well except for the largest one. He remained at the top of the tank, gasping and sometimes floating upside down. I thought he would be dead for sure, but when I awoke the next morning he was fine and was swimming around with the original goldfish of the tank. A few days later, the smallest of the feeders (who ive had for 6 months before moving him) was dead. Again, no prior signs or sickness or visible health problems. He was feeding fine and swimming around with the others. Why are they suddenly dropping dead one-by-one over night? My temps fine, no ones flashing or gasping or scraping.. I cant figure it out...

danasaki

Have you tested your water? Did you quarantine the new fish? Also what kiind or aeration and filtering system do you have? Do you do partial water changes?

Yea Ive tested my water for ammonia and for PH level, both tested fine. I added a Nitrate balancer too. I have an Air-Stone rod that runs across the back of the tank so theres plenty of dissolved oxygen, and I have the Emperor Bio-Wheel filter thats for 50+ gallons. Its funny, because in my two outdoor ponds, I have NO problems whatsoever with losing fish.. but inside, where I have a controlled environment in a 50 gal tank.. I cant seem to find a balance.

Oh and yes, I quarantined the new fish, and I havent done any water changes yet because I just set the tank up on the 26th of December.

I dunno, weird... any possiblity that they were overfed? I say that because it sounds like the one gasping and floating at the top had a swim bladder issue that resolved itself. How often do you test the water, cause if it's a food issue, I would assume the ammonia would go up. I'm no expert tho, so hopefully you can get more input here. Good luck

Well I feed them once a day, 6 days a week. I use a floating pellet, and sometimes i feed them a slice of orange and shelled pees for digestive health. I think youre right tho, I may cut back on the feeding a bit. I try to feed them all equally but its hard because the 2 bigger fish hog the food before the smaller ones find their way to the top of the tank to feed. Thanks for your input tho! Its good to get some feedback from a different point of view, I dont really know anyone else who knows much about fish.

Danasaki, good luck and keep us posted! I have a pond shubie who has a swim bladder problem and when I feed him, he has to float under my plastic alligator to stay upright. After a couple days with no food, he appears o.k. but then when I feed again, same thing. I guess it is maybe a permanent problem and several times I thought for sure he would die. He's still around tho.

danasaki when you add new fish to your pond or tank it can bring out underlining problems with your new or old fish

CashB: You should try feeding them some thawed out, shelled green pees. It clears their digestive system and can help with a funky swim bladder and any constipation that might be affecting your shubie.

DrCase: Can adding new fish to my tank cause these problems even when both parties are healthy?

I have read about the peas on these forums but haven't tried them yet... worth a try since it doesn't seem to get any better. Thanx