I have read many articles that have stated this fact.
therefore, only common goldfish (comets, shubunkins) are "true" coldwater fish.

Fancy's really should be considered semi-tropical fish.

From my experience this is true.


Anyone know why fancy goldfish prefer higher temperatures ??

I'm not sure why but We have three goldfish which we took out of 18 deg water and acclimatised them to 24-25 deg. They are a lot happier and more active at the higher temp. We have two Redcaps and a Lionhead. Here they are

http://i22.photobucket.com/albums/b309/Int...se/100_2242.jpg

I have a 3ft air curtain at the back of the tank and run 6 other air producing items. I also run a second submersible sponge filter with a venturi valve. I have a lot of oxygen in the water.

Hi there. My goldfish experience temperatures ranging from the high twenties down to ten degrees (78F - 52F) and most managed fine. Three fish out of twenty did not do well in the cold water and had to come inside, these were a pearlscale and a telescope, (what was the third one?) durrr.

The ones that managed fine in the cold water included orandas, moors, telescopes, as well as comets and shubunkins.

The benefit of higher temperatures are mainly for digestion, breeding and a stability of bacterial culture in the tank. It can also be argued that a stable temperature reduces stress but it also shortens the life of the fish as they don't experience a winter hiatus.

i had the same experience as above ^^^^^^^

My LFS keeps their fancies in heated tanks (>24 degrees celcius)

When I moved a fish from a warm tank (24 degrees) to a cooler tank (15 degrees), my fish became very inactive and started sleeping at the bottom.

15C is a bit on the cooler side, it's similar to late autumn temperatures and fish will slow down. Even if they were acclimatised over several hours that is a huge drop in temps to experience in one day.

But don't loose sight of the fact that it is normal for fish to have seasonal variation. I wouldn't suggest keeping a goldfish at 15C permanently but for a few months it won't harm them. jmo.

why is it that they'll have shorter live span if the temp is stable? if that's the case, then i wouldnt need any heaters when winter comes (coldest here is about 2-4 C, the tank should be a bit warmer)

If fish experience a "cold" winter they slow right down, some even go into a type of hibernation where they don't eat (or eat very little) for weeks. When this happens their systems are on "standby" and only function minimally for survival.

A fish who constantly lives in 'optimum' warmer temperatures is in top gear all year round and will wear out their systems more quickly than those who stop or slow down for winter. Apparently this is the reason that most professional fancy gf breeders estimate the lifespan for a fancy goldfish at 8 years.

edit: I don't heat my indoor tanks and they only drop to about 18C in winter. Summer they peak around 27-28C. But I don't consider 18C to be a cold temperature so it is unlikely to increase their lifespan. They are pretty active during winter.

Goldfish are a temperate species rather than coldwater. A true coldwater fish lives in water close to 0c all year round.

temperate areas are areas that experience 4 seasons, rite?

fishmerised, do u think goldfish that are exposed to the effects changing seasons will have a higher resistance to diseases?
just like us who are out & about frequently will generally be healthier than ppl who shut themselves up in their houses.
sorry if i offend anyone but ever since i've been living in australia which is heaps more cleaner than indonesia, i've noticed that my body has adapted to the "cleanliness". when i went back to indonesia for holiday, i couldn't eat the food that i used to ate (i got ill) and even the air was stifling, i was constantly coughing & my eyes water.
my point is most of us tries to stabilise the temp of our tanks to the so-called "optimum range" temps. but is it actually more beneficial to the fish's health if we deliberately expose them to the flows of nature, letting the temp drop down to less than 10 C & raise up til 30s C according to the seasons?

sorry rambling

no because over time it may compromise their immune system by constantly having it work hard. well thats just one school of thought, many possiblities

well i used to keep my goldfish at 22c

Goldfish who experience a drop in winter temps and then a gradual rise in the spring are more likely to go into breeding mode, as well. I don't want my fish to breed, so I keep their lighting and temp consistant throughout the year (75 F, 10 hrs. of light) and it seems to work.

If you do wnat to breed, though, simulating the natural seasons is a good way to encourage them.

I do believe that exposing fish to the way nature would treat them is best. I have read from several sources that fish who live in ponds and experience nature and season changes are much hardier, stonger, and prettier fish. I believe I read it in "Fancy Goldfish" by Dr. Erik L. Johnson and Richard E. Hess. I'd have to look that up again...I know I read it somewhere. If I find that info Ill post it.

But fancy goldfish arent bred really to take the same differences in temperature that the common goldie and koi are capable of. The point of the post was to say that fancy bred goldfish are more delicate than the single finned types so need a warmer environment which is true.

I believe people have different opinions about this topic, and as far as I have seen there is no set "proof" that any one idea is correct. I have read many accounts where very knowlageable fish hobbiest say they prefer to overwinter their fish in their ponds because they believe the hibernation process is good for the goldfish. Im talking about fancy goldfish. I have heard many accounts were people have said that goldfish take the seasons very well in ponds, and do not necessarily need warmer water all year long for good health.

Maybe these people just happened to have good experiences exposing their fancies to nature and season changes. I dont know because I dont have personal experience with it.

But I do know that there is no "proof" that fancy goldies do best in a constant warmer water. I think that is a matter of opinion and personal experience.

Could some of it have to do with the temp they grew up in and whether they've ever been exposed to a seasonal temperature flux?

My personal observation (with only one fish here, so grain of salt time): my ranchu doesn't like high temps, he gets freaky when the temp rises over 75...not a happy camper. But, I also let him have a small temperature drop in the winter...perhaps if I'd kept it constant, he'd think warmer water was a nice vacation to the bahamas.

So, my ranchu doesn't like it warm, but I have seen plenty of other ranchus and goldies in general in stores who are doing great at 78-80. There has to be some reason other than just chance. Difference in a yearly cycle or lack thereof maybe? I know that is the case with snails at least...put 'em through a normal "overwintering" (for an excessively mild winter that doesn't get below comfortable) and they don't like higher temps. Just a thought...like shelled invertebrates really make a good comparison to a fish lol

Another possibility just cause my brain is wandering here: water oxygenation? Maybe fish can build up different levels of blood thickness like people can, living at different oxygen concentrations. Like if you move up to the mountains from the plains you feel short of breath for a while until your body compensates. Warmer water is supposed to have less oxygen...right?

you raised some valid points.

Where a goldfish was "raised" has a strong influence!

But i've noticed many pet stores keep goldfish in heated tanks (because all their tanks are connected and share the same water/filtration)

I guess different fish, different preferences then I still think the Japanese's ranchu farmers' method of keeping them outdoor in green water is the best though

Mine stay at 70.....

F of course, not C

This is an interesting debate. d_golem your theory of acclimatisation and developing resistance is a good one, it is often used with humans too. eg. studies show that children who are not exposed to germs, dirt, outdoor time (temp changes) in their toddler years are more likely to develope asthma as they grow older. So with goldfish it may also have a lot to do with the environment in which they were raised from fry.

Most goldfish are breed outdoors in huge tubs or ponds. I know that my local koi farm's fancies are not imported until they are at least one year old (or more). So, one would assume they spent their infancy outdoors and experienced climate/temperature changes.

The koi farm also winter their fancies outdoors where overnight temperatures drop below 0C. The water temp would be less than 10C for the majority of winter. I'm speaking of fancies of everykind imaginable. However, not all fish manage these extremes well, it does put stress on the fish and if they are not strong/healthy enough they will develope illness.

I guess that as a species goldfish are very adaptable and very hardy fish. Even though selective breeding has given us many fancy varieties, for the most part these fancies are bred to live in the same environment as their common cousins.