I had an extra 10 gallon tank that I wanted to set up as a quarantine (emergency sick tank and for observing new fish before adding to main tank). I knew that the tank would be better if cycled so I asked LFS person what would be a good, tough little fish to keep the tank cycled. I was looking at their tank of baby fantail goldfish and he suggested they would be better as a pair, so I bought two. They are 1 inch long not counting the tail. Now I'm reading about these goldfish and it looks like a 10 gallon is barely big enough for one, and way too small for two. Now what do I do? I can't put them in the main 55g tank because it is populated by three Boesemani rainbowfish, and I really don't want to risk introducing another species. I could put them in my 200g pond eventually but not until at least May-June of next year (In Zone 7- I'm sure the sudden shock to 50 degree water would kill them if I tried it now). Can I keep them alive long enough in this 10 gallon tank, with extra water changes and keeping the tank really clean? There is no gravel, and I have 3 filters running....a 30 gph statuary pump surrounded by biofilter media, and two 90 gph Whisper-brand tank filters (the kind with disposable filter cartridges and a sponge pad for bio filtration). How fast will the fantails grow in these conditions and will they be OK for say, six months?

They probally will be, what you are reading is most likely about full grown goldfish, which will get pretty big (probally 8") 10 gallons for 6 monthes sounds okay, expessialy with all your filters. If the fish grow more then 2-3" i would go with a bigger tank. Also, introducing them into the pond now would probally be a bad idea, because 1. They're a little bit too small to handle the cold &2. The shock of a new home&the sudden cold would not be good.

Question: If you have these fish in the quaritine tank, what will you do if you need to use it for quarantine?

Thanks for the reply. I originally figured I could use the cycling fish as "disposables" who would have to risk infection from newcomers, but I grew attached to these little guys in no time. Hopefully I won't need to use the tank for sickness quarantine anytime soon, and I'm definitely going to put off getting any new fish. Next spring I will move the goldfish to the pond and then I will introduce a few new rainbowfish to the 10 gallon. and if they pass muster they will eventually move into my 55 gallon. Then I will have an empty quarantine tank again and will have to start the process all over.

The fantails will be fine in that tank for now. While fantails can eventually grow 8-10 inches long (regular goldfish can grow to 14" or more), that will take years. I expect that even if kept warm and well fed, they won't be much more than 2" by spring. To limit their growth, don't heat the water and limit their food intake. They most likely wouldn't survive going into the cool pond now. How big is your pond? Does it have other fantails?

I understand the desire to have a cycled quarantine tank but, as Animal Love pointed out, what would be done with the fish in there when it was needed? I suggest keeping the quarantine tank dry and only set it up when needed. The reason is that many fish in quarantine or for treatment or going to be treated with medications that kill the good bacteria anyway. Fish often aren't in a quarantine/sick tank for long. It's also wise to disinfect the quarantine/sick tank after use to kill anything bad in there. You can soak the entire tank and any inorganic parts in dilute bleach for a day (maybe half a cup of it in 10 gallons) and then dump that and refill with fresh water with a double dose of dechlorinator. Soak in that for a day, dump, and then either reuse or store for the next time.

Hi Robyn!
In answer to your question, my pond is 200 gallons (2 feet deep) and right now there are only 2 comets (size 4" each) and about 20 rosy red minnows (which I raised from fry born indoors). The comets will be moved to a bigger pond I'm building next year, so I think the fantails will have plenty of swimming room in their new home.

I feel much better knowing that the fantails will be OK in this aquarium for a little while. And I think I like your idea of just setting up a quarantine tank when needed. I've also read somewhere that I could just run an extra filter in my regular tank so it would would be pre-seeded with bacteria and ready for use in a quarantine tank when needed. I don't expect to have to medicate any fish, I really wanted the extra tank for "new fish" isolation, but it is always good to be prepared.

Yes, that's a good point. You can take some filter media from your main tank when needed to put into the quarantine tank.