Temperature: How low can you *really* go? (Whoops, I made a mistake)

[Victorhadin]

Hi guys,

As with many Europeans, a few months ago I looked at my electricity bill and fell off my chair. Resolving to avoid marital trouble, I turned the temperature on my various tanks down a couple of degrees... And it seems, on one of them I overdid it. By quite a lot.

3 months later I cleaned some floating plants from my 350L (90G) SA cichlid tank and found my thermometer stuck among them. Putting it back in it's rightful place I did a double take. Rather than the 25C it should have been, it was between 18C and 19C and had been for months, and the fish were all... OK.

The tank is next to several other tanks in an otherwise unheated converted garage, so it probably gets colder again at night. The tanks are the only heating in the building.

I've since turned the heater on this tank up a little bit but it made me think... How low can we go? Did the fish just think it was a tropical winter?

Pics below. In there I have some young Geophagus 'Tapajos' redheads, penguin tetras, Apistogramma Macmasteri and a bristle nose plec. No ill effects or behaviour changes from any of them.

 

[tlindsey]

Hi guys,

As with many Europeans, a few months ago I looked at my electricity bill and fell off my chair. Resolving to avoid marital trouble, I turned the temperature on my various tanks down a couple of degrees... And it seems, on one of them I overdid it. By quite a lot.

3 months later I cleaned some floating plants from my 350L (90G) SA cichlid tank and found my thermometer stuck among them. Putting it back in it's rightful place I did a double take. Rather than the 25C it should have been, it was between 18C and 19C and had been for months, and the fish were all... OK.

The tank is next to several other tanks in an otherwise unheated converted garage, so it probably gets colder again at night. The tanks are the only heating in the building.

I've since turned the heater on this tank up a little bit but it made me think... How low can we go? Did the fish just think it was a tropical winter?

Pics below. In there I have some young Geophagus 'Tapajos' redheads, penguin tetras, Apistogramma Macmasteri and a bristle nose plec. No ill effects or behaviour changes from any of them.

View attachment 1507644

View attachment 1507646

Wow! Great to hear they thrived through that but for the Apistogramma and Geophagus especially the Apistos I wouldn't go below 78°.
There are cooler seasonal temperatures for Geophagus from the CA regions.

 

[wednesday13]

IMO most people keep their fish in bath water… ive been running temps of 72-74 F for 10+ yrs now for an erray of SA species and others. Ive bred rays at 72 degrees and raised their pups in the same temps just fine. The “cutoff” for me is 68 degrees. Alot of “tropicals” can survive that temp and act normal/seem fine but ive found they will eat much less. Their metabolism slows down. Back up to 70-72 and they start eating more again. IMO theres no need for a tank to ever be over 78 degrees. Being counter productive at that point. Higher temps hold less oxygen and harbor more parasites.

Do ur own tests, make ur own findings of how much u can get away with to save costs . IMO 72-74 is a very safe range for just about anything out there.

 

[jjohnwm]

IMO most people keep their fish in bath water…

Lol, what a coincidence! I brought home a few new fish last week, placed them in quarantine, and 48hours later they were nicely encrusted with Ich. I added a bit of salt, and turned up the setting on the heater; that tank is one of the few I still have that is individually heated, and that's only because most fish I bring home have been maintained in "bath water" and I don't want to shock them by plopping them into a temperature that is 8 or 10 degrees colder.

I watched the tank thermometer carefully for a few hours, as I don't have much faith in the cheapo thermostats in most tank heaters. I was aiming for 86-87F (the room is at 67F), and wanted to take several hours to get to that point. After a few hours more, I peeked into the tank and the thermometer had come loose and floated into a corner where it was difficult to read. I reached in and my heart just about stopped when my fingers touched the water; it did indeed feel like bath water. The fish looked okay, in fact better than just a few hours earlier, but the little orange light indicated that the heater was still heating! I frantically snatched up the thermometer, only to read...80F. Not much higher than some people keep their fish in constantly, but to my arctic-acclimated fingers it felt boiling...and I still had a few degrees higher to go!

It finally hit the desired temperature, and I fiddled with the control knob to keep it there. It's been several days now at 87F and the fish look fine...and the water temperature still astonishes me everytime I touch it. They will be at that temp for at least another week or so; after that they will be back to cool and comfortable, like most of my tanks.

I won't go quite so far as to state that all species we keep are fine in the low 70's, because I'm sure there have to be some that prefer warmer...but certainly most fish are fine at 72F.

I believed for years that temperature stability is extremely important, because...well, because that's what everybody said. I am still fairly careful when doing water changes to ensure that the new water is within about 2F degrees of the old...but now laugh when I see a post where an aquarist frets over whether or not they should raise their tank temperature from 76F to 78F, and then they make sure the change is so gradual that it takes hours or days to complete.

If you are one of those temperature-obsessed fishochondriacs...DO NOT try putting your fish outdoors in the summer months. The temperature in my outdoor stock tanks can fluctuate as much as 12-15F degrees, or even a bit more, within a twelve-hour period, and can vary by that much between the water surface and the bottom of a 22- or 24-inch-deep stock tank. Somehow the fish survive, thrive, colour up and breed in these horrifying conditions...but if you "know" those changes are bad for them, you might get stressed out.

Long story short: fish are not the delicate flowers that many seem to think they are. They are living creatures that evolved in a natural environment, and most of those environments display considerable variation, hour-to-hour, day-to-day and season-to-season. Not just temperature, but also things like pH and other parameters, though temperature is the most likely one to change fairly quickly. When your fish get sick, look for a reason that you can correct rather than an excuse to use as rationalization.

 

[duanes]

Many fish sold in aquarium stores, are not really tropical.
Paradise fish (Macropdus) are found north into Korea and China, and can easily take temps into the 50sF.
Denisen barbs are found in cool streams in India where seasonal temps drop into the 60s.
Certain north Asian Loaches (like the weather loach) can easily take temps down in the 50sF.
When I lived in Wisconsin I kept Uruguayan species that required winter cool downs to be healthy.
In winter I kept them in a kiddy pool on the basement floor where water temps dropped into the 50s in winter.

Above are Gymnogeophagus species, Australoheros species , and southern South American Crenicichla.
A room temp tank for gymnogeophagus shot below, from my Wi fish room.

Even many northern Mexican species of cichlids, tetras, and high altitude live bearers are used to seasonal changes that vary quite a bit.
I have kept cichlids like Herichthys carpintus, and Nosferatu beanii in room temp tanks (with no heaters).
The beanii spawned at temps like the shot of the thermometer below.
Here in Panama heaters are of no use, in fact many aquarists use chillers, but my outside tanks might hit the upper 80s by 3 in the afternoon, but by 6 Am they sometimes drop down into the low 70s.
Not saying these temps would be good for true tropical species from near the equator, but thinking all aquarium fish need 80s all the time, is a misconception.

 

[Simonas]

Got me thinking this post.

I keep both of my tanks at 28 which I think equates to 82

I keep rays, payara, tigerfish eels etc. The tank myst cost me a fortune to heat as its in my garage I may look in to this with a view to dropping a degree or two

 

[Trouser Cough]

Most of us heat a room in our house w/ tank heaters.

Although it's true that resistive electric heaters are 100% efficient it's also true that efficient and cost effective are not synonymous terms. For many of us it could easily be more cost effective to heat the room than to heat the tank.

Years ago I placed 2" thick foam insulation atop my tanks and along the outside of the back wall of the tank as well. In a room that I keep at 70*f I have an 800 US gallon glass tank and I heat it with a 200W heater and whatever frictional losses come off of a half dozen FX6's.

The insulation board doesn't cover the entire top as I have lighting and other access above plus the tank needs air intrusion or there would be no O2 exchange at the riffle. Be that as it may the difference us huge with regard to the amount of power req'd to maintain temp. That would change immediately if the temp in the room were to drop significantly but that would mean I had another, bigger problem.

And yeah, you're right. It's not pretty but it does work.

 

[Fishman Dave]

This is something I have been looking into recently for all the usual reasons and there is a MUCH bigger list of fish than you would expect that can go as low as 18 degrees comfortably and many that go lower still. Currently I have four breeding pairs of blue eyed lemon bristlenose and four trachelyopterus galeatus in my koi grow on tank in over winter temps of 16 degrees.
Next year I am changing out half my fish house (the cooler half) to “temperate” species.
The warmer half is kept at 25 degrees by eight of the tanks individually heated to 25 which in turn keeps the whole room of the fish house at 25 and means that my indoor 1200 ukg pond has no heating at all and remains at 19 to 21 degrees throughout winter with various “tropical” catfish, barbs, arrowana, etc.

 

[jjohnwm]

I think many of us are going this way as energy costs continue to skyrocket. My basement fishroom is definitely moving in this direction. I'm down to only two "tropical" tanks, with the rest now experiencing summer/winter temperature variations, down to 60F or even a bit less in winter.

I find my self carefully examining the native range of many commonly-kept fishes, with an eye towards finding some that can live comfortably at cooler temps than we are accustomed to providing. I just recently noticed how far south the range of the Black Ghost Knife apparently goes; not sure how much the temperature envelope can be pushed with a species that may live in cooler climes, but which is only exported to us from warmer areas.

 

[Cardeater]

I didn't know my heaters were busted in my 125g until I had renewed interest in the hobby. This was back in 2017/18, when I first came up on this site.

I had one of those stick on thermometers an it's just stuck on 78 degrees. I know it's wrong as I have a new thermometer that I have that sticks into the water.

If I don't turn on the heat in this condo, the temperature stays around 70. if it's in the teens or lower outside, I've seen the temp her go to 68.

With all the power heads and filters I have going, the water temp got to about 75.5 when I let temp drop.

For years, the water temp must have been around 70-72 as back then, I only had a HOT magnum a d an old Whisper filter running. Again, I had no idea the stick on thermometer was busted as were the heatters (I guess I'm lucky they just stopped working and didn't get stuck on heat mode."

I had three clown loaches and a pleco back from 1995 and two of the clown loaches are still ove (lost pleco in Sept, probably just due to old age, and there was.an accident where one of the clown loaches had got startled and jump out and I didn't notice till days later).

When I got back into the hobby, I bought new heaters and was all crazy about keeping the temperature near 78-80 for the clown loaches.

I then thought that if the old timers survived for years with the temperature in the low 70s, they are fine now. I actually did keep the thermostat to 72-73 so the tank would stay around 77 but probably don't have to worry about it.

I have a new batch of fish coming in for the first time in 4 years. I took the heaters out of the QT tank. They will be fine at 73-74 degree temps.and I'd rather let the temp.in the ta ks be around room temp then worrying about the heaters being stuck on sometime in the future when they break.