Livebearer Temperatures

Lorekeeper

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Why do I continually hear people recommend that you keep the common livebearers (platies, mollies, guppies and swordtails) below tropical temps? Am I missing something? I'm certain that they're hardy enough to thrive at any temp between 65-85F, but do they actually do BETTER at these lower temps of around 73-74F?

I only ask because I've always kept my livebearers at tropical temps (78F+), and I'd never heard someone say that they do better in these lower temps till I got here. I've heard it from some reputable people as well. Granted, I've got way more experience with mollies and guppies than I do with platies and swordtails, but care is similar.

One of the big reasons I ask is because there's quite a few posts around saying that these livebearers aren't temp compatible with a lot of tropical fish, and I'd argue that's simply not true. I've seen guppies thrive in unheated tanks of around 70F before, and breed like crazy. I've also seen mollies kept in reef tanks that run around 82F, and they also do amazing (much better than mollies tend to do in freshwater, IMO).

So why recommend that these fish won't mix with tropical tanks?
 

Mick Frost

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People tend to rely on their own experiences.
In the wild, guppies are a south Atlantic rim fish, found from South American streams to ocean island reefs, in all different temperatures ranging from 65ish up to the low 80s.
In my experience, anything above 78 seems to shorten their lifespan and increase the chances of birth defects, and anything below 70 seems to weaken their immune system. I dont experiment much, but Ive seen a lot of people treat their fish poorly (usually by accident).
Edited for accuracy (had the wrong coast)
 
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Lorekeeper

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There's definitely a good range to keep these fish in, don't get me wrong. 74-78F is probably the ideal range to shoot for. But these fish can thrive in a lot of conditions, and it's just blowing my mind that there are people trying to turn people off these hardy, beautiful fish, due to a temperature difference that probably doesn't even matter all that much. Personally, I'll always keep my mollies at 78F (unless someone provides evidence that their life is worsened by these temps). But I don't think that the same mollies would have any issues whatsoever living in a cooler tank at 74F.

Just had to kinda blow off some steam, I guess. Not everyone will agree on everything, and I don't expect that to happen - this is a place for sharing information and opinions, and I want it to stay that way. But there's just so little evidence with what these people are saying, yknow?
 

chromedome52

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Mick Frost said:
People tend to rely on their own experiences.
In the wild, guppies are an Indo-Pacific rim fish, found from South American streams to ocean island reefs, in all different temperatures ranging from 65ish up to the low 80s.
In my experience, anything above 78 seems to shorten their lifespan and increase the chances of birth defects, and anything below 70 seems to weaken their immune system. I dont experiment much, but Ive seen a lot of people treat their fish poorly (usually by accident).
Guppies originate from Venezuela and on the island of Trinidad, which are both on the Atlantic. That statement you made is so patently false that it has to be called out. It also tends to make one wonder where you are getting such poor information.

As for temperature preferences for various livebearer species, they are very much dependent on the species and the habitats they come from. Mollies often live in shallow coastal fresh/brackish waters of very warm regions, with several species originating in the tropics. Guppies are tropical, without a doubt, but some of the streams where they are found are under heavy forest canopy, so temperatures are moderated by the habitat. Swordtails of the most common types come from higher altitudes, in fast running water, so they really do prefer very cool conditions. Platies, OTOH, come from muddy backwaters in the lowlands, and temperatures run several degrees higher.

The fact is, however, that many of these fish have been hybridized with species from different conditions, and the resulting aquarium fish are extremely adaptable to a wide range of temperatures. Sometimes if a particular species doesn't seem to want to drop fry, changing the water temperature helps as a trigger.
 

Mick Frost

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chromedome52 said:
Guppies originate from Venezuela and on the island of Trinidad, which are both on the Atlantic. That statement you made is so patently false that it has to be called out. It also tends to make one wonder where you are getting such poor information.
Thank you for the correction, sometimes a decade or two makes memory fuzzy.
 

Brannor

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Lorekeeper said:
but do they actually do BETTER at these lower temps of around 73-74F?
This is where my guppy, dwarf gourami, bristlenose and kuhli live-planted tank is sitting. They seem to do ok - have stopped the guppies breeding now as I've got more than I know what to do with. I based the temp on what was recommended for each species and found what is the middle point that suits all of them.

I'm still working out if the change in temperature from just over 78 down to this range is affecting some of the plant growth, or if it was the introduction of far less light (5h midday siesta). As my tank is still under 6 months, I'm trying to work out how to stop the staghorn algae... and what affect the water temp has on its growth.

-G
 

sfsamm

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I get appalled at some of the people here and their entirely over specific no margin for difference care demands that they toss around. It turns people off of some of the hardiest fish like live bearers because people insist in temp incompatibilities that simply are not the case especially in most tank raised fish. Not to say all fish are temp compatible, not by a long shot. But to insist that fish whose ideal temp is 2-3°F different from another are completely incompatible is complete nonsense. Even in wild environments most of the fish we keep see seasonal and even day/night temp variations. They are alright in their ranges and most are often fine even above/below their ranges for short periods of time.

Temperature does affect them, low temps generally slow growth especially in fry and higher temps can decrease life span due to increased metabolic rates. But I can honestly say I don't know of a single fish that must be kept at a specific degree temp and is going to kick off or fall deathly ill if that temp varies a couple degrees.

Temp incompatibility in my book is someone who wants to keep Goldies with their Angels, not someone keeping a center range 75° fish with a center range 78° fish or a 78° with an 80°.
 

75g Discus Tank

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It’s just breeding rate. Livebearer won’t breed as much in cooler waters IME. Also, their metabolism is slower so they live longer(theoretically).

I keep my feeder endlers(not used for feeding) at 78-80 degrees because endlers like warmer waters, but other livebearer like guppies prefer cooler water.

Fun fact, but the thing that separates guppies and endlers in the wild is the temps. The temps are warmer where endlers live and guppies dint like those waters(due to being from cooler waters).

Also, I belive that global warming is the reason for endlers being extinct in the wild as the guppies are now more heat tolerant and the guppy DNA has tainted all of the remaining wild endlers so they are no longer 100% endlers.
 

CraniumRex

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Glad to read all the info here. I'm considering adding livebearers to a few of my tanks and am labouring over the dizzying array of info I have read and seen on them concerning temps.

I have a few species - namely panda corys and Bolivian rams - where I have seen the same very wide range of temps along with some very strict instructions from certain people on keeping them in cooler water (though many, many sites suggest the rams in particular "do fine" at 78). I'd like to expand some of my options and I think from what @sfsamm has said, I'm struggling over something that is not as critical as I might imagine (a few degrees here or there).

Question for folks who know: How can you tell what temp any fish might prefer? Is spawning behaviour indicative of preference or is it just a temp change that marks the change of season (like more light, not the temperature, makes a dog shed)? Could one tell by behaviour and activity level? I would assume longevity is the best indicator, but as @Chromeome has stated, stock can vary in origin, so varying temps are acceptable. What do you look for when you decide what's optimal? Would you ever shift the temp, say, 2 degrees for 6 months then rotate so that any fish out of its prescribed temp has a turn? Just throwing it out there.

Part of me loves the idea of being able to mix fish as I prefer, but then a true biotope has a certain appeal, doesn't it?
 
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