Fish that benefit from a cool down period? Need advice

[Rafini]

Howdy MFK,

I am about to set up a 75g and I would really love the idea of not running a heater.
I would be willing to run a heater on the lowest setting during the coldest months.
(it was -38 C in January for a week, but we can also have mild winters)
In my house the lowest it really ever drops at night is about 16 C (61 F), and that is because we like to keep it cool while we sleep., I would also be willing to shift this a few degrees.
If this is going to prove impossible, I am completely willing to use a heater. I do not want to cause any suffering for my aquarium inhabitants, right now I`m planning and researching.

As I understand it, there are Uruguayan and Argentinian species that actually like a cool down period and will benefit from lower winter temps.
I would prefer the aquarium be a somewhat regional biotope but I would also be willing to add some indian or asian species if it becomes too difficult to find correct species.

The temps:
In the summer the aquarium will be between room temp and higher, whereas in the winter it will be at room temp during the day but dipping to that 16 c (61F) or so at night.
The nightly drop in temperature would occur for roughly 4 months depending on the weather.

I would like to stress that the fish will not be kept at the lower threshold for any longer than a night, so I am not looking for a coldwater aquarium, but more of a temperate set up with species that can benefit from or tolerate lower temps around 16 C (61 F)

My research has told me that there are cool water corydoras species (Paleatus) and possible some plecos
I know about the Gymnogeophagus species and they would be a worthy addition.
As for schooling fish I believe Bloodfins and Buenos Aires can take pretty low temps. as previously stated, I would be willing to switch to a danio species or something if thats better suited)

I`m looking for advice and anyone who has had experience with a Uruguayan, Argentinian, Temperate etc aquarium
Which species would work?

Thanks,
Rafini

 

[dan518]

Some of the more southerly apistogramma spp would be ok at those temps. There are also the northern centrals, n beani, h cyanoguttatus etc.

 

[dan518]

If your after a Asian type setup rhinogobius spp would work well at that temp.

 

[duanes]

I have kept many Uruguayans,at room temp in my poorly insulated fish house when living in Wisconsin.
The ambient temp in the house would drop into the low 60s in winter, and that drop seemed to be enough of a cool down for them.

Above Australoheros fry, directly below Cichlasoma dimurus "Bella Union"., in an adjacent tank.

Below Gymogeophagus quilero

quilero spawn as the room heated up into the 70ss

/i also kept then in ponds and brought them into an unheated basement in winter where temp dropped into the high 40s.

Pair spawning in the upper right.

 

[Rafini]

dan518
I have never seen Rhinogobius for sale, I occasionally encounter stiphodon.
I would be interested if I could source some locally.

duanes I was hoping you would chime in!
I did keep red ceibal once a few years ago, I actually was intending to lower their temp and they died unexpectedly.
I later discovered my heater malfunctioned and only the high temp tolerant fish survived, it was in the high 80s I think.
Heres a pic:

Beautiful fish, he would go from electric yellow to a stripey brown almost instantly

The only Uruguayan I seem to encounter on a semi regular basis is Gymnogeophagus Balzanii.
Not sure if they would get too big for a 75g, in my previous experience they grew slowly.
The aquarium has a 40g sump system and I plan on regular water changes.

DId you keep any dither species or corydoras/catfish with your uruguayans Duanes?

I don't mind hunting to find the right cichlids, but there has to be some activity going on in the tank in the meantime lol

 

[duanes]

Balzani will easily handle only slight cool downs, I kept the room temp all year round (60s-mid 80s).

They did well with Uruguayan Cory's, below female above, Buenos Aires tetras also work well as dithers.

 

[Rafini]

So if I bumped it up slightly I could Keep Balzanii?

Is 75g enough space for them?

Still interested in some other midwater species or corydoras

 

[duanes]

I kept balzani at room temps, I didn't use any heaters on their tanks at all, no need to bump up, those temps just reflected the normal winter/summer swings in ambient temp of the house.

 

[Tobiassorensen]

Ive kept geophagus braziliensis in tanks with no heaters with my fishroom dropping below 20c in the winters and they do perfectly fine. IME they tend to do better in a little cooler water and i only bump the temp a little when an fishstore nearby gets hos stock on fry from me low.

 

[duanes]

Ive kept geophagus braziliensis in tanks with no heaters with my fishroom dropping below 20c in the winters and they do perfectly fine. IME they tend to do better in a little cooler water and i only bump the temp a little when an fishstore nearby gets hos stock on fry from me low.

I've done the same with those of the braziliensis clade. Even had a pair spawn in a 300 gal Rubbermaid stock tank in the yard in Milwaukee where night time water temps averaged around 68'F.