Signs that your unheated aquarium is a no-go

[MRTom]

After a few months of trying out this unheated tank idea, I thought I'd start collecting some of the warning signs that a tank really needs to be heated. So far I've only run into two signs where the best treatment was a warming of the tank:
- Red gills on a betta: These guys really do like their tanks warmer, and my having them unheated was only due to a broken heater... which I discovered by noticing the redder gills... so there you go. Tropical fish like tropical temps.
- Ich: fish that need warmer temps seem to be more susceptible to ich. This was the hint that the online store that sold me japanese ricefish (oryzias latipes), a coldwater fish, instead sent me celebes (oryzias celebensis). After adding a heater and much salt treatment, these guys seem to be back on track.

That said, with the exception of that misidentified tank, the rest of the unheated tanks seem to be hanging out just fine. I keep my room between 68-70 constantly, so I'm not really doing cold water. If you guys run into other signs or issues with your tanks, please share so we can exchange notes!

 

[ShortyKiloGyrl]

I have 1 tank with fw angelfish in it and they as well are unheated so to speak. But the house is as well 68-70 all the time as well. And I've kept guppies and a small pleco in an unheated tank before without issues. No deaths or illness. I guess it varies upon species of fish and their hardiness?

 

[hyp3rcrav3]

"Red gills on a betta"

My Betta is in a small tank on my mantle. It is unheated but it has a "Small World" sponge/carbon filter on it run by air. Red gills are usually a sign of nitrate poisoning.

For angel fish to be happy they need to be between 74 and 82 degrees. They are from the Amazon and tributaries.

Guppies originate in Seminole Country, that is, from Florida swamps across the Southern US and Northern Mexico. It may not freeze but it can get cool down there. They can handle temps like 68 but they like it between 70 and 75. Water is usually 2 degrees cooler than the air around it (don't quote me on this). Related fish just a little further south like platties, swords, and mollies like between 72 and 78.

We have 3 koi in an unheated 70 gallon by the window doing just fine. It is more an issue in the summer when the water needs to be changed more often. Nitrates are more reactive when it is warmer so we need to change the water more often to keep from poisoning the fish. Water changes also helps with dissolved oxygen since the fish metabolism is higher in warm temperatures.

 

[MRTom]

Good point on the betta and nitrates. I was thinking along the lines of
heater failure -> increased stress -> increased nitrates -> red gills, all other things being constant. It may be that she may have been ok with just a water change and no more heater, so maybe I'll give that a try next?

I'd agree with angel fish and warmer temps, not a species I'd have guessed for a strictly room temperature tank, but if someone is successfully caring for them and breeding them at such, I'd love to hear more about it!

To get more back on topic I think the purpose of this thread is twofold. It would be good to have a post somewhere that says "here are some species that we know are compatible with our room temps and water supply in the WA area". And it would also be good to have another post that says "here are some common problems and some recommendations on what to do about them." This is a start to collecting some of that info!

 

[LuminousAphid]

so far i have only had one problem with an unheated tank, and i think that might have also been due to the stocking level- it is an extremely small tank. a couple of h. formosa jumped out of the tank (i always go topless  8) ) or swam into the micro-hob outlet and got stuck in there, and even now they are always hiding and not really active. i guess this might be a sign of a no-no species for unheated too, just general lethargy and inactivity

i'm sure that angels can survive at room temp, but i'm also sure that they would be a little happier with warmer temps. i have my 20 with 7 baby angels at about 80, and they seem super happy and growing fast. always very active and hungry.