Full agreement with you, practical experience with cold water fishes is more important than just theory from books.Is that a generally accepted set of temperature parameters...or is there much disagreement on that?
Perca flavescens, very similar to your Perca fluviatilis, are widespread in North America, including here in Canada where they live under thick ice for months each year. Water temps are in the 35F range in many instances...but the species lives for years in basement tanks that never get below 55F. I had several Perch in a tank in my parents' basement when I was a kid, and that small group was installed when I was in the first year of high school (grade 9) and was still going strong when I graduated from grade 13 (I think it only took about ten years...). I doubt that water ever got colder than 55F, and probably never quite hit 70F, so nowhere near the range they would have experienced in the wild. They grew decently well, although not as large as wild fish, and they coloured up each spring as well, although I never witnessed actual spawning activity.
That was in extreme southern Canada, but we still had solid ice each winter for a few months and the fish saw very cold temps in nature. I am fairly certain that our winters there were somewhat harsher than those in much of Europe; I'm positive that the winters where I live now are much harsher than anything Europe has to offer, and P.flavescens thrives herel..but surviving extreme cold is not the same as requiring it. I'm sure that they would have suffered if kept at 70F room temperature year round, although they certainly live through several months each year at that temp or higher in the wild...but I don't think they need those extremes either.
I think that in many cases, other problems arise with the keeping of native fish, some of which quickly or eventually result in death...and that the lack of extreme cold is used as an easy and convenient excuse.
Goldfish can easily survive under the ice each winter...but the vast majority of captive goldfish spend years or decades at room temperature. Different species, of course, but an example of the same idea. My Perch weren't kept in a species tank; they were in a "bait-shop community tank", as my Dad called it, and lived with Pumpkinseed Sunfish, Bullheads, Emerald Shiners, a succession of Bullfrog tadpoles and other assorted local catches. All those species seemed to do well without freezing temps.
European themed aquarium.
- Thread starter esoxlucius
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I don't think that European fish find it "difficult" in summer. They've evolved to cope with the seasonal variation in temps. What is clear though is that some love the warmer temps, such as tench and carp, and others such as chub, bream, roach, rudd and barbel are, what I'd call "in betweeners". Then you have pike, perch and zander which love the colder temps.
We don't see mass tench and carp deaths in the middle of a brutal winter, and we don't see mass pike, perch or zander deaths in the middle of a scorching summer.
The fish who prefer warm water slow right down in winter, almost to the point of hibernation. And the fish who prefer cool water tend to go deeper in the summer to seek out those cooler spots. They all cope in their own way.
I believe the warm water fish (tench and carp) and the "in betweeners" (chub, bream, roach, rudd and barbel) will be fine with our non heated aquarium temps, but the cool water fish (pike, perch and zander) may struggle to some degree. They can't exactly move to deeper waters in a fish tank to search out those really chilly spots which outside winter temps offer them.
I think that is the key point in whether those that prefer colder temps are going to thrive or just survive in aquariums.
We don't see mass tench and carp deaths in the middle of a brutal winter, and we don't see mass pike, perch or zander deaths in the middle of a scorching summer.
The fish who prefer warm water slow right down in winter, almost to the point of hibernation. And the fish who prefer cool water tend to go deeper in the summer to seek out those cooler spots. They all cope in their own way.
I believe the warm water fish (tench and carp) and the "in betweeners" (chub, bream, roach, rudd and barbel) will be fine with our non heated aquarium temps, but the cool water fish (pike, perch and zander) may struggle to some degree. They can't exactly move to deeper waters in a fish tank to search out those really chilly spots which outside winter temps offer them.
I think that is the key point in whether those that prefer colder temps are going to thrive or just survive in aquariums.
Its not just about the phyical temp with cool or warm water itself that causes problems,
Cold water has the ability to hold more oxygen than warm water,
where warm tropical water may max out a 5 ppm dissolved oxygen, water at 50"F, like that of the average temp of Lake Michigan most of the year can hold 10 ppm disolved oxygen, and even become super saturated.
Fish in the tropics have evolved to live in a much lower dissolved oxygen level than fish of the north.
Some that come from stagnant water are able to use atmospheric oxygen to supplement the lack of DO in that environment.
Add to that nitrate levels, Lake Michigan has an average nitrate concentration of 0.50 ppm to 1.25 ppm whereas in many aquariums, a nitrate level of 20ppm, is an accepted norm, and nitrate itself hinders a fishes ability to use that dissolved oxygen.
So put a cool water fish in a room temp tank, combine that with the wimpy water movement in most tanks (compared to nature), and on top of that allow nitrates to creep up, and you basically starve that fishes ability to breath.
Cold water has the ability to hold more oxygen than warm water,
where warm tropical water may max out a 5 ppm dissolved oxygen, water at 50"F, like that of the average temp of Lake Michigan most of the year can hold 10 ppm disolved oxygen, and even become super saturated.
Fish in the tropics have evolved to live in a much lower dissolved oxygen level than fish of the north.
Some that come from stagnant water are able to use atmospheric oxygen to supplement the lack of DO in that environment.
Add to that nitrate levels, Lake Michigan has an average nitrate concentration of 0.50 ppm to 1.25 ppm whereas in many aquariums, a nitrate level of 20ppm, is an accepted norm, and nitrate itself hinders a fishes ability to use that dissolved oxygen.
So put a cool water fish in a room temp tank, combine that with the wimpy water movement in most tanks (compared to nature), and on top of that allow nitrates to creep up, and you basically starve that fishes ability to breath.
That ^ is useful info! Serious fishermen, like serious aquarists, know that oxygen content varies inversely with temperature; hearing that increasing nitrates hinder a fish's ability to utilize that oxygen is a revelation for me at least.
Don't forget that water gets denser and denser as it cools, like most fluids...but once it hits about 40F it's at its densest point. Further cooling makes it become increasingly less dense, which is why ice floats. If water were a "normal" liquid that just gets denser and denser until it freezes, lakes would freeze solid at the bottom first and ice would just get thicker and thicker down there. Gad...no such thing as ice-fishing...the end of human civilization!
We were ice fishing just the other day, with water temperatures just under the ice showing 35F...but water on the bottom was 40F. So all those fish were sitting on bottom to stay warm! Lol, I'm sure the fish are following the oxygen, and the baitfish, and the available cover, and a host of other obscure factors that affect them in various ways. It's clear that they aren't simply wandering around with thermometers in their mouths, looking for the coldest water.
I do believe that all species...fish and otherwise...struggle in extremes, whether those be extremes of temperature, oxygen or any other variable. A Whitetail Deer or a tiny Chickadee outside in -50F temperatures doesn't look miserable...but it is struggling to survive and many of them don't survive. A fish in a frozen-over lake struggles to find a combination of temperature, oxygen levels and enough food to survive...whether in February or in August. Opposite extremes, different stresses imposed upon the fish...but in both cases some will survive and some won't. And of course different species will have varying capacities to survive different extremes. A "warmwater" Bullhead may not be as adaptable in extreme cold as a Trout...but will survive oxygen-deprived, overheated stagnant summer water that would kill a Trout in short order.
So, avoiding those extremes in our tanks might mean that the fish are indeed thriving, as opposed to merely surviving out in the lake. If a group of fish in an aquarium all live through the winter...but the population in the lake all suffer a die-off from "winter-kill" of 25% each winter...which group is thriving?
Don't forget that water gets denser and denser as it cools, like most fluids...but once it hits about 40F it's at its densest point. Further cooling makes it become increasingly less dense, which is why ice floats. If water were a "normal" liquid that just gets denser and denser until it freezes, lakes would freeze solid at the bottom first and ice would just get thicker and thicker down there. Gad...no such thing as ice-fishing...the end of human civilization!
We were ice fishing just the other day, with water temperatures just under the ice showing 35F...but water on the bottom was 40F. So all those fish were sitting on bottom to stay warm! Lol, I'm sure the fish are following the oxygen, and the baitfish, and the available cover, and a host of other obscure factors that affect them in various ways. It's clear that they aren't simply wandering around with thermometers in their mouths, looking for the coldest water.
I do believe that all species...fish and otherwise...struggle in extremes, whether those be extremes of temperature, oxygen or any other variable. A Whitetail Deer or a tiny Chickadee outside in -50F temperatures doesn't look miserable...but it is struggling to survive and many of them don't survive. A fish in a frozen-over lake struggles to find a combination of temperature, oxygen levels and enough food to survive...whether in February or in August. Opposite extremes, different stresses imposed upon the fish...but in both cases some will survive and some won't. And of course different species will have varying capacities to survive different extremes. A "warmwater" Bullhead may not be as adaptable in extreme cold as a Trout...but will survive oxygen-deprived, overheated stagnant summer water that would kill a Trout in short order.
So, avoiding those extremes in our tanks might mean that the fish are indeed thriving, as opposed to merely surviving out in the lake. If a group of fish in an aquarium all live through the winter...but the population in the lake all suffer a die-off from "winter-kill" of 25% each winter...which group is thriving?
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Couple inputs.
1. It seems in many or most of the states in the US a license is needed to keep natives as pets. They are never (to be) sold at local fish shops either. Correct me if I am wrong, please.
2. Some colder fish statistics. We have been trying some colder water fish here in Florida. We are able to keep the maximum temp down to 82F in our 25K gal, with fans and with the tank being a couple feet below the grade. We started out with 5-6 golden orfe that is the Eurasian Leuciscus idus several years ago that in the wild are thought to never see temps above 65F. They die for no clear reason, but probably the temp/DO. We have been down to the last one for a year or 2 now, and it doesn't look like it is thriving, despite the invariably great appetite it looks thin and haggard.
The beluga sturgeons born in 2018 have been doing ok for 3 years with us 2020-2023 but this is hardly long term.
Wels catfish also doing ok, 2016-2023, 7 years with us, used to be in 240 tanks that get up to 90F in the summer time but as of 3 years ago the wels went into the said 25K with no more than 82F.
IDK if Himalayan / golden mahseer are considered temperate water or not but our pair has been doing very well for 7 years 2016-2023, in the 240's and now in the 25K.
Hi fin banded Chinese loach we had struggled with, lost about 4 in prior tries, now trying a couple again, don't know what I am going to do to keep them cooler in the coming hot season.
Same with Siberian sturgeon in the warmer 240 gal tanks, lost all 5 when the season turned hot.
Bowfin we lost, IDK if the temp was it or something else.
Phoenix barbs thrive.
Yellowcheeks we lost but these can handle warmer temps it seems. They can't handle when the stirring stops.
I am sure I am forgetting some more.
1. It seems in many or most of the states in the US a license is needed to keep natives as pets. They are never (to be) sold at local fish shops either. Correct me if I am wrong, please.
2. Some colder fish statistics. We have been trying some colder water fish here in Florida. We are able to keep the maximum temp down to 82F in our 25K gal, with fans and with the tank being a couple feet below the grade. We started out with 5-6 golden orfe that is the Eurasian Leuciscus idus several years ago that in the wild are thought to never see temps above 65F. They die for no clear reason, but probably the temp/DO. We have been down to the last one for a year or 2 now, and it doesn't look like it is thriving, despite the invariably great appetite it looks thin and haggard.
The beluga sturgeons born in 2018 have been doing ok for 3 years with us 2020-2023 but this is hardly long term.
Wels catfish also doing ok, 2016-2023, 7 years with us, used to be in 240 tanks that get up to 90F in the summer time but as of 3 years ago the wels went into the said 25K with no more than 82F.
IDK if Himalayan / golden mahseer are considered temperate water or not but our pair has been doing very well for 7 years 2016-2023, in the 240's and now in the 25K.
Hi fin banded Chinese loach we had struggled with, lost about 4 in prior tries, now trying a couple again, don't know what I am going to do to keep them cooler in the coming hot season.
Same with Siberian sturgeon in the warmer 240 gal tanks, lost all 5 when the season turned hot.
Bowfin we lost, IDK if the temp was it or something else.
Phoenix barbs thrive.
Yellowcheeks we lost but these can handle warmer temps it seems. They can't handle when the stirring stops.
I am sure I am forgetting some more.
This is the pertinent study (first posted by neutrino,) a lot of difficult scientific details to wade thru, that connects nitrate to the ability of fish to process oxygen, in the presence of elevated nitrate.
Simultaneous exposure to nitrate and low pH reduces the blood oxygen-carrying capacity and functional performance of a freshwater fish | Conservation Physiology | Oxford Academic (oup.com)
Simultaneous exposure to nitrate and low pH reduces the blood oxygen-carrying capacity and functional performance of a freshwater fish | Conservation Physiology | Oxford Academic (oup.com)
Wow, Viktor...reading about the temps you must contend with really hits me hard with the old "greener grass" shovel...right between the eyes, lol.
I have been gradually moving towards cooler water fish, including natives. Not only is the cost of heating water for tropicals becoming very prohibitive, but not needing to worry about power outages and dangerous temperature drops is very liberating. But if I were to return to more tanks requiring supplemental heating, at least providing that heat is a simple procedure and, even at today's prices, not insurmountable; heaters are cheap. I shudder to think of the cost of buying and running chillers for a large collection of fish like the one you have.
My latest foray into the chilly world of natives is a recently-captured Burbot; the water in its tank is stable now at 54F, and I expect it to hit 60F or perhaps 65F at the height of our short summer. After years of warmwater tanks, reaching into this one and feeling the relatively icy chill can be...unsettling. When icefishing in an unheated tent, reaching into the near-freezing water in the hole is momentarily a very warm sensation, since the air is much colder than the water; it only feels cold if you leave your hand in for awhile, and it is immediately uncomfortable when you take it out. But in my basement, the air right now is about 60F, so reaching into the colder water in the tank is a shock; the idea that "cold is bad!" is pretty firmly entrenched and must be consciously fought.
I have been gradually moving towards cooler water fish, including natives. Not only is the cost of heating water for tropicals becoming very prohibitive, but not needing to worry about power outages and dangerous temperature drops is very liberating. But if I were to return to more tanks requiring supplemental heating, at least providing that heat is a simple procedure and, even at today's prices, not insurmountable; heaters are cheap. I shudder to think of the cost of buying and running chillers for a large collection of fish like the one you have.
My latest foray into the chilly world of natives is a recently-captured Burbot; the water in its tank is stable now at 54F, and I expect it to hit 60F or perhaps 65F at the height of our short summer. After years of warmwater tanks, reaching into this one and feeling the relatively icy chill can be...unsettling. When icefishing in an unheated tent, reaching into the near-freezing water in the hole is momentarily a very warm sensation, since the air is much colder than the water; it only feels cold if you leave your hand in for awhile, and it is immediately uncomfortable when you take it out. But in my basement, the air right now is about 60F, so reaching into the colder water in the tank is a shock; the idea that "cold is bad!" is pretty firmly entrenched and must be consciously fought.
I've never thought about large scale chilling of our tanks. We bought a 500W chiller that's good for up to a few hundred gallons. It doesn't seem to lower the temp even by a degree in our 25K, which had been kind of expected and then proven too.
Heat pump, such as an AC, is an efficient way to cool a room with fish tanks.
Heat pump, such as an AC, is an efficient way to cool a room with fish tanks.
Here in Panama, chillers are the norm, even for tropical species that prefer temps in the 70s., and especially goldfish
And I doubt they are any more economical than the use of heaters elsewhere. (probably just the opposite.
I don't use them, preferring to keep natives used to the heat
But to keep my tanks temps stable (among other things), I put the main tank in the shade under a roof, and the sump in the open, in direct sun, but use water lilies and floaters like salvinia and water lettuce in the sump, to deflect the most intense sun.
View attachment IMG_0187.jpeg
And I doubt they are any more economical than the use of heaters elsewhere. (probably just the opposite.
I don't use them, preferring to keep natives used to the heat
But to keep my tanks temps stable (among other things), I put the main tank in the shade under a roof, and the sump in the open, in direct sun, but use water lilies and floaters like salvinia and water lettuce in the sump, to deflect the most intense sun.
View attachment IMG_0187.jpeg
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