Mollies are a little bit bigger, and mollies seem to have more shapes. Other than that, they seem the same.

 

Mollies and platies are very similar. Mollies get bigger. Sexing on Mollies is way easier. Platies, and Swordtails can interbreed among each other. IMO platies are hardier and breed faster.


P.S. Swordtails are better! ;D

 

Platies tend to have shorter body's rounder bodies. The mollie is a longer sleek fish. Mollies were the fish fish I ever kept back 13 years ago. They are fun fish.

 

Other then what is mentioned above, platies are soley freshwater fish, while mollies are brackish (but have been adapted to freshwater).

 

Mollies will pick at little algaes on decorations.

Platies use the decoration to hide out and boom-chicka-wow-wow.

 

I found mollies far more difficult to keep back when I lived in Florida and my water was liquid rock. My platies thrived whereas I could never keep mollies healthy. I'm not sure if this is typical but I've steered clear of mollies since then.

 

Platy and Molly

Hello Wing...

I'll take the comparison a little further. I keep large tanks of Fancy Guppies and have read a little on "Livebearers" in general. All will do well with a little standard aquarium salt in the water. A teaspoon per every five gallons of your water change water is sufficient. I've been using aquarium salt in my Guppy tanks for a number years with good results.

Platys are much hardier. Mollys aren't as tolerant of mistakes in tank management. They're very picky about water conditions, like water temperature and also diet.

If you keep Platys, you can skip a water change every so often, but you'd better get used to weekly water changes of at least 50 percent with Mollys. Maybe we need to be doing large, weekly water changes anyway. That's what I do.

Mollys are also very senative to cramped tanks. A pair of Mollys are fine in a small 20 G, but if you keep other fish with them, a 50 G minimum is needed.

Can't recall anything else. Hope this info. is helpful.

B

 

Hello Wing...

I'll take the comparison a little further. I keep large tanks of Fancy Guppies and have read a little on "Livebearers" in general. All will do well with a little standard aquarium salt in the water. A teaspoon per every five gallons of your water change water is sufficient. I've been using aquarium salt in my Guppy tanks for a number years with good results.

Platys are much hardier. Mollys aren't as tolerant of mistakes in tank management. They're very picky about water conditions, like water temperature and also diet.

If you keep Platys, you can skip a water change every so often, but you'd better get used to weekly water changes of at least 50 percent with Mollys. Maybe we need to be doing large, weekly water changes anyway. That's what I do.

Mollys are also very senative to cramped tanks. A pair of Mollys are fine in a small 20 G, but if you keep other fish with them, a 50 G minimum is needed.

Can't recall anything else. Hope this info. is helpful.

B

Good afternoon, B...

Mollies are actually quite hardy, in fact they are one of few aquarium fish that can easily go from full fresh to full salt. Mollies are probably more hardy than platies simply because they can regulate their internal organs to take in and expel chemicals. 10 pairs in a 20 would be sufficient with a little room for babies to be born. While using aquarium salt is okay, I would not reccomend willy nilly in case of an overdose and the fact that the TDS would fluctuate.

D

 

As someone who has messed around with live bearers for years, I've never had a problem with Mollies being finicky, and certainly never needed 50 gallons to keep more than 2 or had to do water changes every week.

I'm not sure where that is coming from, I've never heard that before, and it certainly doesn't match my experience.

The two things to watch out for with mollies:
1. They don't like high nitrates. A few live plants in the tank help keep Nitrates in check.
2. They like hard water with a high PH.

As long as you are doing those two things, they should be fine. Some species require a little salt in the water (Black mollies tend to have skin issues without salt), some are fine without it.

Note: This is in regard to your "normal" mollies and balloon mollies. I have never kept Sailfin Mollies, which are much larger than "normal" mollies.

I've always had good luck with mollies and platies. Guppies on the other hand have given me issues.

 

I have had lots of mollies in the past. I even had a few in my reef tank at one time. Never had any trouble with them dying or not breeding. On the other hand, I could never keep platys alive. Until just this year they always died on me. I have seven Mickey Mouse Platys now and they have been alive 6 months or more. That's a record.

 

I have found that mollies are not as timid as some platys. They both breed very easily but for some reason my young platys get pregnant too young sometimes which causes them to get sick after birth. Also I strongly recommend aquarium salt when keeping mollys. The aquarium salt tends to give the fish a better chance of staying healthy. Both are great fish but if I had to pick between a molly or a platy I would pick molly hands down because of there curious nature. Mollys love to peck at sinking algae wafers and it's fun to watch.

 

Funny how different our experiences are. I was an accidental serial killer of not only the mollies I talked about but guppies also. In heavily planted tanks with liquid rock for water and big water changes each week. Tried the salt trick too.

I finally stopped buying them all out of mercy for the fishies. My house was fishy death row.

Anyway, I've recently fallen in love with livebearers all over again and am putting platies in my 75g. They're so colorful and peaceful. I love them!

 

I found the babies of the mollies grow faster than the platy by far.

 

I find mollies to be pretty hardy as well. Right now, I'm keeping wild sailfin mollies in my 30g planted tank as well as a Rubbermaid tub on the back patio. They breed constantly, the males are relentless.

Fry survive much better in my densely planted (packed with guppy grass and milfoil) outside tub. For most of the summer, I fed lightly once a day and pretty much left the tub alone.

Off topic but if you want hardy, try mosquito fish. Those things bred like crazy in the tub for 2 months with no supplemental feeding. The tub is covered too.

 

I know it is a bit late to be responding to this thread but I wandered into the discussion and have a couple potentially useful additions. For Mollies and Platies I find the fish have very different personalities. Platies tend to be more aggressive in schools than Mollies and tend to scare much more easily when alone (not around others from their school). Mollies are much more inquisitive even when alone and tend to be fairly gentle even with other fish (the male can be an exception to this if he wants something). Baby Mollies seem to develop a little slower than platies. Molly fry are more comfortable moving around the tank sooner than Platy fry (tend to stay in the plants towards the bottom for longer). Neither fish needs any salt in the water if you follow a no water change maintenance regimen. As 'no water change' will likely cause many of you to claim I am abusing my fish I will elaborate a bit.

I have 2*~35 gallon planted tanks that have been evolving over the last 5 years into completely self sustaining systems. I never change the water any more and the chemistry has been rock solid for 3 years now. Over they years of experimenting with all kinds of maintenance schedules by far the most stable results and the best response by all my fish has been NO water changes. Obviously, I need a good number of various plants (to scrub the water) and I do need to ADD water once in a while. The Platies, Mollies, snails, algae and plants all reproduce like crazy. The Plecos and snails keep the algal growth in check. The plants compete for nutrients with the algae as well, keeping a nice balance. I remove excessive growth once or twice a month and clear the filter intakes as often as necessary to keep good water flow (once to three times a week depending on tank load and food given). Lights are standard florescent shop lights (I replace these cheap bulbs often). Below are some specifics.

Tank 1: Microreef style tank (back of tank filter)

Platies - 25 at any given time.
Pleco - 2 (1 male 1 female)
Snails - lots...
Java moss
Algae
Various leafy green plants
Various natural wood species from nearby reservoirs
Several pieces of bleached coral collected from beaches.

Tank 2: Standard tank with canister filter.

Black Sailfin Molly - ~10 at any given time.
Platies - ~25 at any given time.
Pleco - 1 male
Snails - lots...
Java moss
Algae
Various leafy green plants
Various natural wood species from nearby reservoirs.
Several pieces of bleached coral collected from beaches.

I only share my experience to offer an alternative to the common practice of large water changes. The common wisdom is to help your fish and keep chemistry stable you HAVE to make water changes. I have found exactly the opposite. Stability for me comes from keeping the same water in the tank. I put a good deal of effort, research, and experimentation into finding wood, rock, coral, fish, plants and other aquatic species that build a self sustaining ecosystem.

Additionally, I have begun to mix fish (platies) from tank to tank to increase genetic diversity. This practice is the most controversial in my mind. The reason is I was shocked to see how negatively a platy behaves when it is taken from the tank it was born in an placed in a new environment. Also, I have found the larger dominant females in tank 1 will chase down and eat any fish from tank 2 they can fit in there mouth if it is not from their school.

I would love to hear thoughts or other's experiences with a self sustaining process or more about Mollies and Platies. I really love both species, they are wonderful self sustaining fish!!

 

Livebearers; I appriciate you jumping into this thread! I have just "found" I quite like the molly's & I actually think I may have a platy that was sold to me as a molly but they're in the same tank together so I don't really care too much I think I may end up with both as I prefer a mix with a wide variety of color vs lots of 1!
Also b/c of your "no water change method". Honestly a few mths ago I rehomed my giant goldfish & had the thought of getting down to 1 tank to cut back on my fish chores as I a busy mom & was feeling "burnt out". I told hubby I wanted to go a low maintenance single community tank in the 30gal. Well that hasn't worked out quite the way I said (I still have 3 tanks... but 1 (male guppy tank) has been given to the 11 year old for care. then we have the 10gal planted betta tank b/c betta's are my "#1" & my boy got his tail nipped up by the black phantom tetras & honestly I missed the interaction with him while I am in the kitchen. & the 30 gal planted which thanks to a dwarf gourami massacre a mth ago, I'm in the middle of figuring out my stocking & an appropriate "cleaning crew".....
my tried tested & true cleaning crew previously were killed off in the massacre so now I'm juggling again but many of these are back in 1 or both of my planted tanks or are on my list just waiting for the stores to have some when I go in! Otto Suckermouth catfish, sphixi & mystery snails, Clown pleco, baby to Juvie sized Bristolnose plecos, Cory catfish (I prefer julii & hasbrosus) & leopard loaches.

 

Differences Between Platies and Mollies

Mollies can typically get a little bigger. Often you see brightly colored platies, but mollies are usually more neutral. Typically you can put more platies in a tank than you could mollies, with the same tank. Mollies typically have fins that can sort of flow (not really that much), whereas platies do not at all. Personally, my favorite molly is a Dalmation Lyretail, and fave platy is probably either Green Lantern or Sunburst.

 

My favorite thing about mollies is that when I have kept them they don't tend to eat their babies at all. I've heard other people say they will but I have never experienced it. In fact usually when I see them in pet stores there are a bunch of babies swimming around in the tank. The babies are usually born pretty large so this may help them seem less like food. Platys on the other hand always ate their babies in my tanks.