# Heaterless temperate/sub-tropical aquaria



## MWood (7 Oct 2019)

I saw a Filipe Oliveira video where he was running an aquarium without any heater, with a pair of honey gourami (Trichogaster chuna) as the centrepiece. It got me thinking about which other species are happy in the high teens/low twenties, outside the usual suspects (White Clouds, Paradise fish, Variatus platy etc etc). The lack of equipment and spend on electricity appeals to me, though I do appreciate the advice suggesting having a heater set low just in case.

I snorkelled with a bunch of Devario regina in supisingly cool water in Thailand last year, I suspect various other
Danios and Devarios would be suitable. I actually had a heater failure last Christmas, with my Emperor tetras living (and breeding) without for a couple of weeks while I was away, to no visible ill effects.

Anyone else had success with other species at this kind of range?


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## Edvet (7 Oct 2019)

In my believes most fish can thrive in 20 degr Celcius (don't know how much that is in Kelvin, Fahrenheit or Peasants per square mile )


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## mort (7 Oct 2019)

I find seriously fish is a great resource as it shows natural water temperature variations for the fish. You will see most have quite a wide range and its this natural variation that helps improve health and lifespan, keeping them at a high constant temperature isn't ideal for lots of species.

I set my heater to 21c as I keep pencilfish and its the bottom of their range, I'm sure they could cope with a degree or two lower but I want them to thrive rather than survive. if you are looking at the high teens then barbs are a great family to look into as well as danios.


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## jameson_uk (8 Oct 2019)

A quick list from when I looked into setting one up (some are probably 20°C plus so borderline).

Most danios
Rosy barbs
Cherry barbs
Several Cory's (I was looking at pandas)
Otos
Paradise fish
White cloud mountain minnows
Hillstream loach

I am always a bit wary of natural habitat temperature info.   I suspect many of these species are pretty far removed from wild species and have been bred for generations in warmer water but should be ok.


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## Tim Harrison (8 Oct 2019)

Check this out from PFK How to set up a temperate tank - that looks tropical!


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## mort (8 Oct 2019)

jameson_uk said:


> I am always a bit wary of natural habitat temperature info.   I suspect many of these species are pretty far removed from wild species and have been bred for generations in warmer water but should be ok.



For heavily bred commercial strains you might be right but I don't think their lack of hardiness in mainly due to being kept to cold. I'm not sure how many generations it takes to reduce temperature tolerance but I'd wager the average fish doesn't suffer from this unless it's been heavily modified by inbreeding. Lots of commercial fish are bred in areas with natural seasonal water temperature changes and after watching a few vid of commercial farms I was very surprised by just how cold the water got (they had clown loaches seemingly happy in 16-18c water for part of the year). I've also seen white cloud mountain minnows that overwintered with ice on the ponds no problem, even though they have been heavily bred, and seriously fish states captive fish tolerate cooler water than some wild caught fish.
I do completely agree you should be careful choosing which species you try.


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## jameson_uk (8 Oct 2019)

mort said:


> .
> I do completely agree you should be careful choosing which species you try.


Indeed, this was just being wary.   As per the PFK article above I suspect many stores keep fish in near tropical conditions and you might need to help them adjust back towards the values they see in the wild.  No idea on genetics but I always kind of assumed that if they are bred, sold and kept at fairly static temperatures then it would be their ability to deal with temperature swings that would go before they changed what temperatures they would be happy with (probably complete rubbish as I have nothinf on which to base this but would be interested if anyone actually has any scientific info)

For the OP I missed out a couple of species I couldn't remember
Odessa / Ticto barbs
Denison's Barb
Bloodfin Tetra
Buenos Aires Tetra


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## Matt @ ScapeEasy (8 Oct 2019)

Really interesting thread this... I'm looking to set up a leaderless tank in the near future for the same reasons as the op.  Think I will make it a hillstream tank initially and probably transition to a palaudrium type later on.  Always good to try new things!

A few more species to add to the list:
Glowlight tetra
Least Killifish


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## MWood (8 Oct 2019)

Thanks all, some excellent species there. And agreed - I think seasonality in terms of gradual changes of temperature is definitely something that's missing from most aquaria. I've got most tanks set at around 22/3, but they've got up some way past that during the Summer months. 

I've been considering starting something around either Sawbwa resplendens and/or Danio tinwini myself, only as I'm keen for some asian species at the moment. I seem to recall that there are a few Apistogramma which prefer cooler temps, including borellii. Aphanius mento is a pretty spectacular killi I've heard of being kept outside year round (!). I suspect this list could get rather long.  

I can definitely see a Least Killifish paludarium! or Gymnogeophagus for something at the other end of the scale....


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## Matt @ ScapeEasy (8 Oct 2019)

Matt @ ScapeEasy said:


> Glowlight tetra



That should read Glowlight Danio... is there a mod who wouldn't mind changing this for me?


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## MirandaB (9 Oct 2019)

In my various unheated tanks I keep hillstream loaches,Rhinogobius species,Aphanius Mento and Rainbow shiners but there are plenty more out there to consider


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## Regent (9 Oct 2019)

This is handy as well
https://www.practicalfishkeeping.co.uk/features/hang-out-with-the-cool-crowd/

What I'm struggling with is mid sized community fish


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## Regent (9 Oct 2019)

I hadn't realised some of the Apistogramma liked it that cool, thanks!


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## Edvet (10 Oct 2019)

If you search for fish from Argentina or Urugay region they do well in roomtemperature 18-20 C


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## mort (10 Oct 2019)

Regent said:


> I hadn't realised some of the Apistogramma liked it that cool, thanks!



If I remember right there are three (or possibly more) apistogramma species that do well in temperate waters for at least part of the year, borellii which is the most peaceful , trifasciata which I've heard can be more aggressive and commbrae which I don't really know anything about.

Central American fish can be found in waters that dip to 16-18c and I've seen breeders of wild caught live bearers such as sword tails,  endlers and even guppies drop the temperature to room temperature with them. I'm not sure how mass produced stains would cope with that considering jameson_uk considerations above. There are also some other central American cichlids that might fit the bill but they tend to be large.

You also see variatus platies quite commonly in temperate sections at the lfs and don't forget amano shrimp.

I do think the end of the practical fishkeeping article sums it up nicely when it says don't keep them in perpetual winter and see the lower temps as a part of a yearly cycle.


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## Conort2 (10 Oct 2019)

Regent said:


> This is handy as well
> https://www.practicalfishkeeping.co.uk/features/hang-out-with-the-cool-crowd/
> 
> What I'm struggling with is mid sized community fish


Any of the barbs from India should do fine, so denisoni, filamentosus, Arilius etc. They get to a good size. Most of the devario and larger danio species will be fine too. I think most cyprinids from India will be fine with lower temperatures.

 Some of the rainbow fish from higher altitudes too can be kept cooler. As also explained any of the Argentinian cichlids like gymnogeoohagus etc. 

There’s quite a few options you can go with depending on what sort of set up you’re looking for.

Cheers Conor


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## zozo (10 Oct 2019)

I wonder how they come up with Temp recommendations for tropical fish. Other than the obvious assumption, it's from the tropics with an average such and such in its natural habitat than it must be, keep it at that, better safe than sorry than to experiment.

Tho most fish have a rather wide and not fully documented natural distribution. Then take for example a country like India, that has about every climate there is to offer from the Himalaya mountain streams all the way down to Sri Lanka. Than the Oreichtys mainly found up North even as far north as mountain streams in Nepal. Still, the lowest recommended temp for this fish is 24°C? And I've kept those fish for years in 20°C.

Same goes for many South American fish sp. i kept years at 20°C without any issues. Occasionally even bellow that in freezing winters whit the central heating off and the house getting pretty cold nights.

I know the LFS like to keep all fish at 28°C, but that is mainly to weaken parasites, such as Ick and others. Then suddenly transfer them to a colder tank and they might get sick, but actually came in already weakened and infected with a latent present parasite.

I did my fair share of thinking about it and i think this is the main reason why most temp recommendations are in the high range. But a healthy fish and since its a cold-blooded, in a healthy tank, it can take far less and stay healthy.


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## Conort2 (10 Oct 2019)

I think the problem is everyone thinks of the tropics and thinks 28 degree water, which is probably true for the main river channels. However a lot of our fish are tiny and from small forest streams, these are often under shade and probably more near the 20degree mark. I used to keep most fish hot however I think it shortens their life span as they’re cold blooded. I keep everything at 20 degrees now and have no issues whatsoever, every thing is active and feeds well. And that includes fish from places like the Rio negro which places specify should be kept Warm.

Cheers

Conor


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## Edvet (10 Oct 2019)

Most smaller waterways in the actual jungle are quite warm ( 25-28C) ( amazonas territory so Peru, Brazil, Colombia etc) as you can see in the reports from http://www.tomc.no/default.aspx


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## Conort2 (10 Oct 2019)

Edvet said:


> Most smaller waterways in the actual jungle are quite warm ( 25-28C) ( amazonas territory so Peru, Brazil, Colombia etc) as you can see in the reports from http://www.tomc.no/default.aspx


Nevermind ignore me then lol! 

Edvet, I believe you’re an actual vet? Is it actually beneficial to keep fish cooler if they can take it due to being cold blooded and slowing their metabolism or am I over thinking things?  

Cheers

Conor


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## Edvet (10 Oct 2019)

Not sure slowing down metabolism causes longevity in vertebrates ( i don't think so).


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## Regent (10 Oct 2019)

So at the moment I have.
12 Odessa barbs
10 glow light danio
2 bristle noses

The tank is 400l though an odd size 36x 24x 30inchs tall. In a peninsula layout. The tank is low tech and currently 23 Deg.  Although it hit 27 when first set up in the summer, so there will be seasonal variation!
I'm struggling with what else to add.
I'll start a journal when I get time because I likely need some aquascaping input.

Those apistos may be just the thing. I was considering going up to 24 and adding pearl gourami.



 


 
It's grown it alot since these!


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## mort (10 Oct 2019)

Laetacara dorsigera is one I've considered for my 21-22c mimimum tank. Nannacara anomala are also a possible if you go a little warmer.

I love pearl gourami as they are really graceful but I worry the barbs might nip them and from my personal experience the glow light danios are pretty boisterous as well.


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## Regent (10 Oct 2019)

I've been considering Cryptoheros nanoluteus and the electric blue Accra as well as they will both tolerate down to 22.

Yes the danios hold they're own easily against the barbs who are actually very chilled! I lover pearls, but I worry they'd be nipped and not like the amount of current.

There are a lot of fish happy at 22 to 23 and I suspect many options we don't think would tolerate it would.. I just need a couple more tanks to fill with different selections!


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## Regent (10 Oct 2019)

Wow I've just realised how many typos there are in that!


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## MWood (16 Oct 2019)

Really interesting stuff. Funnily enough I have Laetacara dorsigera at this temp at the moment.


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