Gymnogeophagus balzanii in temperature below 40 f

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Make note that a habitat (location) variant of a fish from the Amazon region, even if its the same species, may not tolerate what a variant of the same species from Bella Union in Uruguay.
Unique climactic conditions of either area would have, thru natural selection weeded out those of without certain tolernenss.
I have kept Cichlasoma dimerous from bella Union at 50" F, but would not expect a variant from Rio Parana in the middle of Brazil, to tolerate the same conditions.
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The same could be said for the more northerly variant of Gy balzani.
I kept the Uruguayan variant of balzani, with southern S American variant Cory's..
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For Belgium, it would be prudent to do research on location variants from southern Uruguay and Argentina, where colder winters are common.
 
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Absolutely. Mind you that Bella Union is in the very furthest NW corner of Uruguay and has some different fish that are found in the south... but the average daily lows in the winter (July) there are 48F. I've caught plenty of piranhas and balzanii there and further south on the Rio Uruguay in Villa Constitucion. We've collected serpae tetras there, Pim cats, Apistos and all sorts of "tropical" species. In the summer, it gets really hot there: We measured that the water where we collected Apistos, Cichlasoma, Cory longipinnis and other fish was 99F.


I keep mostly Uruguayan fish (and Mexican goodeids) in my fishroom and try to replicate the weather down there. I let temps drop into the 50s for a couple of months of the winter and let it get hot for a couple of months in the summer. The heat and longer days really induce spawning.

Gymnos and other Uruguayan fish aren't really "cool water fish" - more like fish that need seasons - cool in the winter and hot in the summer - to do their best. I've kept them in a cool basement fishroom that's basically the same temp (upper 60s / low 70s) all year.... and I got some but not a lot of spawning. It wasn't until I moved them to the garage, where I got bigger temperature swings that breeding was like gangbusters.

Thanks for posting that; very interesting! Quite a few species listed on there that I found surprising. Piranhas, Black Ghost Knife, way more Gymnogeophagus species than I realized, tons of catfish/plecos, Motoro rays, etc. Makes you wonder what else could be kept in cooler tanks than we normally expect.

My local retailer/importer has an "ill-tempered" 24-inch-plus Jau catfish, and that's on the Uruguay list. Maybe in my outdoor pond year-round? :)
 
I will tell you that for me personally a paradigm shift in how I keep fish has been setting the heater for 62 degrees on my Uruguay fish and Central Americans my building has (now) tons of natural light and no AC so it gets plenty warm in the summer, and most of the fish are outside anyway in the summer. I’m tired of fragile fish. Can’t stand the idea that a fish is supposed to live its entire life at 76-78 or whatever and that temperature swings are stressors. Fake fish. All my fish see temperature swings day to night year round now and I only leave the lights on for a couple hours after it gets dark so I can enjoy the lit tanks in a dark room but their day night cycle is pretty close to the natural one where I live. This year the Uruguay tanks will have no heat, The fish outside overwintered without issue here in coastal Ga lowest water temp I recorded was 38. Even my Costa Rican fish have been down to 54 (water) for 2 nights
 
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That's pretty much how I keep mine in Maryland, although we've had such a weird spring - 80s one day, 50s the next - I've set the heater for 68 for the past couple of weeks.

As an aside, Uruguayan fish, especially Gymnogeos, I've purchased from places that have kept them in year-round tropical conditions tend to succumb to weird ailments.


I will tell you that for me personally a paradigm shift in how I keep fish has been setting the heater for 62 degrees on my Uruguay fish and Central Americans my building has (now) tons of natural light and no AC so it gets plenty warm in the summer, and most of the fish are outside anyway in the summer. I’m tired of fragile fish. Can’t stand the idea that a fish is supposed to live its entire life at 76-78 or whatever and that temperature swings are stressors. Fake fish. All my fish see temperature swings day to night year round now and I only leave the lights on for a couple hours after it gets dark so I can enjoy the lit tanks in a dark room but their day night cycle is pretty close to the natural one where I live. This year the Uruguay tanks will have no heat, The fish outside overwintered without issue here in coastal Ga lowest water temp I recorded was 38. Even my Costa Rican fish have been down to 54 (water) for 2 nights
 
"Paradigm shift" is certainly not overstating it. I think back to when I started in the hobby, and "tropical fish" were often thought of as just that: purely tropical. Temps simply "had" to be maintained at a constant 78F or you were doomed to failure. Common sense tells you how silly that sounds...but that was the way much of the literature and common wisdom told us to think. I modified my ideas over the years but it's only been the past 5 years or so that I have done much thinking along the lines of copying the natural yearly rhythms of light and temperature.

It's pretty wonderful to watch the colouring-up and heightened intraspecific interactions in Amecas, Gymnos, Jordanellas and others as the thermometer creeps back up into the high 60's.

But...I admit that when my G.rhabdotus were outside in 50F water last year, I was very anxious when I drained that pond the next week to take them inside for the winter. My wife is still laughing about my incredulous "Holy crap...they're alive!!!" as those lovely bespangled fish emerged in the net. :)
 
Not just alive... but doing great, I'd imagine.

What's interesting about Uruguay is that while there are seasonal temperature changes, there really isn't a rainy season the way that there is in Amazonia. The key to breeding many of the fish from there is to mimic the natural rain and drought cycles (e.g. don't do water changes for a bit... and then do a big one with rain water).

I'm hoping to coax a pair of Uruguayan pikes to spawn by adding more current (and food) ... like it's spring. Colored up, fat and feisty but no eggs - at least that I can find.


"Paradigm shift" is certainly not overstating it. I think back to when I started in the hobby, and "tropical fish" were often thought of as just that: purely tropical. Temps simply "had" to be maintained at a constant 78F or you were doomed to failure. Common sense tells you how silly that sounds...but that was the way much of the literature and common wisdom told us to think. I modified my ideas over the years but it's only been the past 5 years or so that I have done much thinking along the lines of copying the natural yearly rhythms of light and temperature.

It's pretty wonderful to watch the colouring-up and heightened intraspecific interactions in Amecas, Gymnos, Jordanellas and others as the thermometer creeps back up into the high 60's.

But...I admit that when my G.rhabdotus were outside in 50F water last year, I was very anxious when I drained that pond the next week to take them inside for the winter. My wife is still laughing about my incredulous "Holy crap...they're alive!!!" as those lovely bespangled fish emerged in the net. :)
 
"Great" is an understatement. They, along with virtually every type of fish that has been allowed to vacation outdoors for the short Manitoba summer, looked absolutely stunning.

I'm starting to think that an outdoor season for most fish falls into the same category as the same treatment applied to houseplants. No matter how carefully you tend to their needs and nurture them indoors, there is simply nothing like a few months of natural sun, natural temperature variations and plenty of natural food in addition to that provided by me to bring out the best in them. I haven't had any mature cichlids outside yet to spawn (hopefully this year...), but many other types of fish have produced beautiful broods under the warm sun. If there's one thing better than finding your fish bigger, healthier and more colourful than when you put them out, it's finding that you now have several dozens or hundreds more than you started with.
 
Not just alive... but doing great, I'd imagine.

What's interesting about Uruguay is that while there are seasonal temperature changes, there really isn't a rainy season the way that there is in Amazonia. The key to breeding many of the fish from there is to mimic the natural rain and drought cycles (e.g. don't do water changes for a bit... and then do a big one with rain water).

I'm hoping to coax a pair of Uruguayan pikes to spawn by adding more current (and food) ... like it's spring. Colored up, fat and feisty but no eggs - at least that I can find.

Here's someone who has bred Uruguayan pikes if you haven't read it yet.

 
MonsterFishKeepers.com