# Mollies vs Swordtails - which is hardier?



## LariM78 (Nov 2, 2010)

Hi all,

Can someone with some experience of both species help me out? I've been trying to keep mollies for the past year since I set up my tank and I just can't seem to keep them alive. I acclimate the fish correctly and regularly test the water and the water conditions seem stable enough and stays at the following levels.

NH3 = 0
NO2 = 0
NO3 = 10ppm
pH = 7.5
Temp = 28C

I do water change once a week. I know some people will advise adding salt but then this will affect some of the other fish I have and fro what I've read, mollies can do quite all right without salt. I've currently got 4 mollies in quarantine which will be moved to the main tank this coming weekend. If they do not survive I don't think I'm gonna be getting mollies again, I can't take the disappointment when they don't make it. I'm thinking instead of getting sword tails if or when these mollies die but are they hardier than the mollies? I've also only ever had fry from mollies that were bought, they have the fry and then don't have any more after that - I guess that does point to some environmental factor that they don't like, perhaps I will do better with swordtails...

Any thoughts?


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## GuppyNGoldfish (Mar 28, 2011)

What are the other fish in your tank? You can add salt as long as the other fish don't have a labyrinth organ. I have mollies and swordtails. The mollies are in a 20 gallon, 3 adults, 19 fry, with 3 platies. When I first had gotten mollies I had an Ick outbreak killing 3 of 4 original mollies I had, once I fixed that problem I got new mollies from a different LFS and they were fine in the tank. My molly has given birth once since Ive had her, its been 2 months since she last gave birth. I'm not sure how long a molly birth cycle is, but both of my females are very fat, I can't tell if they are pregnant or just fat. If a birthing cycle is longer than 2 months, then mine aren't breeding. I also have 2 swordtails in a 10 gallon and they are very hardy.


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## jrman83 (Jul 9, 2010)

I'd get Swordtails over Mollies any day. I have the same problem wthl Mollies. A buddy of mine that has been keeping fish for 40yrs refuses to buy Mollies. Says they die too easy and get sick very easily. I have learned this is true and have stopped trying to own any. Once mine are gone, I don't plan to try and get more.


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## NeonShark666 (Dec 13, 2010)

Mollies are really a Brackish water fish from the Gulf Coast region of North America. They need a little salt and hard water. Most other livebearers like hard water but don't need need the salt. I keep my Mollies in pure Salt Water and they do great. 28C is at the high end of the Mollies temp requirements. Most other livebearers like a temp below 25CF. Mollies don't like dirty water so make sure your Nitrates aren't high.


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## allllien (Apr 6, 2012)

In my opinion, Mollies are hardier than swordtails anyday, but you need to get the good quality ones to begin with. 
I recently had a disease outbreak in one of my tanks and all the swordtails got sick (I lost quite a few of them too), but the 3 Mollies were bulletproof / untouched by the disease! They were the only 3 fish that didn't get sick out of the whole tank! 
I'm convinced it's the 'poor-quality' Molly's that give everyone the trouble.

PS. I don't use any salt either


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## navigator black (Jan 3, 2012)

Mollies as available in the pet trade are usually hybrids of several Poecilia species - salt-loving coastal latipinna, and sphenops from salt-free interior Mexico. If they are sailfins, they can be latipinna, velifera or petenensis hybrids. I consider them to be fairly delicate fish - your water must be clean and hard for most of them. 
Mollies get a bad rap as beginner's fish, but for me, after 40 years fishkeeping, I consider sailfin mollies to be tougher to keep than Discus.

Pet-shop Swordtails are crosses between Xiphophorus species - helleri, variatus, alvarezi and sometimes maculatus. They are tough as nails and ideal for beginners with large enough tanks for them to swim in - 3 foot tanks are best. 

neonshark is talking about Poecilia latipinna, which is coastal from Florida through the gulf into Mexico. It's a great fish with local populations living in pure freshwater all the way to seawater. South of them, you get velifera, with the same habitats, and petenenis, from pure freshwater. You also have sphenops, mexicana, orri, gillii and butleri - it's hard to generlize about mollies.


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## BBradbury (Apr 22, 2011)

Hello Lar...

My friend Dave, who's been keeping different tropical fish for about 50 years, says Mollies aren't the best choice if you're new to the hobby. They're great fish, but are the least hardy of the "Livebearers".

To maintain them, you need to pay very close attention to the water properties, diet and water temperature and need a larger than normal tank, 20 gallons per pair of Mollies. He says there are too many hoops for the average tank keeper to jump through for this fish.

B


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## NeonShark666 (Dec 13, 2010)

Mollies come fom Brackish water areas of Mexico and Central America and. in my opinion, need a little salt. I have kept Mollies in pure salt water for years and they are doing great. Swords like hard, high ph water, like most Livebearers but don't need vey much salt. Both fishes do well with clean water in the low 70's.


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## navigator black (Jan 3, 2012)

Neonshark666- I've found mollies in pure freshwater in Mexico. Poecilia latipinna, velifera and orri come from brackish water. Poecilia sphenops, butleri, mexicana, petenensis and gillii don't - they are often found with swordtail types in hard alkaline water. I caught P. mexicana in the drinking water supply stream of a small Guatemalan city - no saltwater there.
Poecilia caucana has shown up here in shipments of Apistogramma from Colombia - from very low hardness and a pH around 6.6 to 6.8. The group is very adaptable, even if each individual species isn't.
Most of the pet shop mollies are multi-species hybrids, with a lot of latipinna and sphenops in them. I always add salt to the mineral mix I need for my soft tap water, but it's one mineral among several. If I had latipinna or velifera, I would go with a lot of salt, as you suggest. Your suggestion is good for sailfins, since they'll all have coastal mollie DNA, but short fins follow a different set of rules.
Either way, they are not really easy fish when compared to swordtails, which are.


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## allllien (Apr 6, 2012)

I had an aquarium shop tell me a couple months back that they didn't ever get Mollys in because they kept dieing on them! I can't believe so many people have so much trouble with Mollys when I find them the easiest fish in the world to keep  I don't use any salt and never even test my water! The only thing I'm doing differently is keeping them in cold water -Maybe this has a lot to answer for? I'm not recommending it, I'm just saying how I keep my Mollies without any problems  This is an unheated, indoor tank (In Australia) -Our winters get fairly cold and I've seen the temperature get as low as 10C in my tanks (although that's fairly extreme) -generally it sits around 20C -24C and gets as high as 31C in the summer. The fish don't seem at all bothered by the temperature swings and breed regularly.

Here's a pic of my favorite Sailfin Molly  He looks even nicer now he's grown a bit (The other fish in the photo are pregnant Swordtails)

Aquarium Gallery - Orange Sailfin Molly


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