Mollies in coldwater...?

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I agree with WattaMelon. I have kept wild sailfin mollies in both cool tanks and warm. I have noticed that the older they are, they can handle cool temps better. But when 2'' or under, they definately do much better when kept in warmer water (>72-73 F). I also get much better activity, reproduction and fry development in warmer water.
 
We have mollies here in NC where I live, they withstand freezing winter temps, they are the same species as the ones caught in Florida but they are a geographical variation. Across much of their range mollies do live in very cold water in the winter but they do not grow or reproduce while they are cold. The really big mollies live where they are warm pretty much year round and in brackish water.
 
I think it depends what your deffinition of coldwater means. I don't heat any of my livebearer tanks.. and my room doesn't get below 65 but once or twice during the winter. personally I've seen more issues with the sailfins not kept in brackish water then not kept in warm enough water. They are a very hearty, adapatable fish. any extreme is not good for them. But keeping them in pure freshwater ime is more detrimental then keeping them in relatively cool or "room temp" water. and to attain their 6" sizes they need room. I kept a breeding trio in a 55 and felt at times this was even cramping their style. not to mention kept happy and healthy they will produce literily hundreds of fry a month. The tank was in my basement and was not heated. but the basement was insulated/finished. At a guess I would say it got down in the mid to low 60s in the winter and well near 80 in the summer.

personally I don't agree w/ "cranking the heat up" on any fish, dissolved O2 levels and ammonia spikes ect can get downright deadly at over 80 deg temps. yes in the wild they get exposed to these temps. but not over an extended period of time, things cool off in the evening generaly, and the wind/air currents do also play a factor in temp, and O2 levels. and when they do get exposed they don't just breed better and flourish.. i've seen small holes full of dead ones. and the ones in larger bodies of water are capable of finding warmer or cooler water as they see fit. they don't have that option in captivity.

Would I suggest keeping them year-round outside in a pond? No. Year round in a house 60-75 absolutely okay. over 80, if you want to take that risk.
 
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Thanks for the response guys.
My intentions was to put some in an outdoor pond. I knew they were hearty fish and wondered if anyone else had them in a pond. I'll just stick with koi. Thanks again all
 
IMG_1800.JPG IMG_1799.JPG I have mollies outside and in from 15 gallons to 55 and my inside tanks are 82* and outside in the winter 82f and in the summer can get to 85f but I usually add ice packs after 83f and they breed like crazy, my 55 is totally over stocked, trying to find someone to take young ones regularly, so far no luck. I am seriously surprised I don't loose fish, but I have 2 bio-tanks, a double bio sponge and I keep it very oxygenated and have to uv lights attached to my filters.
 
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Its all about getting the right location variant, as said by moontanman, if you get the Carolina variant, no problem, if the ones available are endemic to the Yucatan they will probably not survive the drastic temp fluctuations.
Just as with sunfish, there are Lepomis species species from Florida, and Lepomis in Wisconsin, most Florida variants wouldn't last the beginning few weeks of winter in Wisconsin.
 
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