Animal Stories - Mollies

Animal-World Information about: Mollies

   The colorful active Molly, Short-finned Molly, Sailfin Molly, or Mexican Sailfin Molly has long held the position of being a most popular fish because it is peaceful, relatively hardy, inexpensive, and readily bred!
Latest Animal Stories
Anonymous - 2012-12-31
i have one male molly in a community tank, is it okay if i add more males? i really don't want any babies. thank you!

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  • Jeremy Roche - 2013-01-01
    Mollies will usually do just fine with multiple males.
Rob - 2012-11-30
I have 4 mollies in a tank and 2 of the 4 have almost like a hole in their gill coverings does anyone have any idea what they are? They act fine for the most part they still eat and all but IDK. :{

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Anonymous - 2012-10-28
My mollies had babies.  Do I need to seperate them?

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  • Jeremy Roche - 2012-10-28
    Yes.  They will eat their fry.  If you cant, put some breeding grass in to give the babies a place to hide.  You will loose some.
Cassara - 2012-02-23
About 3 months ago, my molly had a batch of about 25 fry. While sexing them today I found that I had no males. Are all mollies born female and then turn male later in life? Or is it just a batch where it was all females?

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  • Clarice Brough - 2012-02-26
    Wow that's amazing, but not unheard of. It's believed that a number of influences can affect the sex of the offspring in fish. These include the age of the spawning adults as well as environment influences including temperature, pH, and light levels. There are a number of fish that will change sex, but Mollies aren't one of those.
  • Wythori - 2012-07-13
    Ignore last comment, I read it wrong. It takes about 6 months for the anal fin of the male molly to become the tell-tale gonopodium. Before it develops it will look like a female. Males will be slimmer and slightly smaller though.
Candice - 2012-04-01
I've got a 75 gallon tank with a lot of live bearers. About 20 fish in all. Recently while doing a water change I noticed some baby mollies so I caught them and moved them to a nursery tank. This was about 3 weeks ago. Later in the day after I finished the water change I noticed another baby swimming around a rock cave in the corner. Never could catch this swims too fast for me to grab with the net. Deciding that Nature would probably take its course I left the baby alone. Three weeks later, the babies in the nursery tank are quite large and resembling balloon bellied mollies. The baby left in the big tank is still quite small and seems to have escaped being eaten. Do I need to put more effort into catching this fish since it doesn't seem to be growing like its siblings?

If necessary to know, my fish are:
5 mollies (1m 4f)
5 balloon belly mollies (1m 4f)
4 platys (1m 3f)
7 guppies (2m 5f)

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  • Jeremy Roche - 2012-04-02
    No real need. Remember the one with the big fish is more active so it is burning more calories and probably not getting spoiled with as much food since it is getting the big fishes leftovers.
Animal - 2012-03-31
If you buy female mollies from an aquarium with differing sexes, there is a strong chance that they become very suddenly pregnant, so be careful when buying females when there are males in the tank.

Samantha - 2010-07-15
I just bought 3 mollies today from pet smart. My husband and I went out to dinner and came home to find that one of them had given birth to 5 babies. I can't tell the difference between male and female and have NO idea how to care for them. Can someone PLEASE help. I will check back here for any answers or feel free to email me at

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  • Jeremy Roche - 2012-03-13
    If you look at the molly page on Animal World you will see the top picture(Silver Lyretail Molly) look at botton fin near anus. Thats a female. Now look at the third picture(Silver Balloon Molly), thats a male.
  • Odell - 2012-03-12
    You can tell if it's a male or female by the anal fin. The male
    will look like a flat hook and the female like regular fishes.
kester apostol - 2011-12-21
Hi, I have 4 different molly females and 1 male black molly..will that be enough?..or do I need to buy another one?

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  • Charlie Roche - 2011-12-21
    Yep, that's enough.
  • abhishek sahane - 2012-02-11
    Keep it as it is because if there are more males they fight. More females and if there is strong male it is easy for breeding
Michele G. - 2011-07-12
HELP!!!! I recently bought 4 silver mollies. They are in a 55gal tank with 2 plecos, 7 catfish, 3 alge eaters and 4 swordtails. Less then a week after I brought them home, I noticed one had a big belly and a gravid spot. A little bit later..we had babies. This was fine with me. Two weeks later...we had MORE babies. Now - I just noticed EVEN MORE babies. They all appear to have a rounded anal fin. None of them appear to be males - who is getting them pregnant? Do I have the Immaculate Concepcion of the fish world???

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  • Charlie Roche - 2011-07-12
    I think there must be a male but you don't need a male for females to lay eggs - but I am not sure about fish. You need another tank - 55 gallons is too small for 7 catfish, 2 plecos, e alge eaters and 4 mollies and 4 swortails. Rule of thumb every one each of adult fish needs one gallon of water. You need to separate out the fish in the tank as they are going to get agressive on each other (or stress or ill). You also need a tank for babies cuz the bigger fish are going to see food when the fry swim. Immaculate conception - probably not but stuff happens. Good luck and have fun.
  • Amelia - 2011-10-23
    Mollies and other livebearing fish are almost always pregnant when you get them. They can also get pregnant w/ a male and then get removed to an all girl tank and they will continue to have babies about once a month for a few months! Yes, they only have to do it once! Also they are closely related to platys and swords...I think they can procreate w/these. My surprise comes from all your fish NOT eating most of these babies/fry and leaving you w/10 or less each batch...natural selection in their world! Why haven't your other fish helped a bit?
  • zeke - 2012-01-16
    Dude you should get those baby mollys - wait till they grow up and you can make a quick buck with them:D
Anonymous - 2011-12-11
Please help, input appreciated:
I have a creamcicle Lyretail Molly that is laying down on the bottom of my 20g tank. He has done this MANY times before, but somehow has recovered from being, what I was conviced was, dead. The first time I noticed his deteriorating condition, he appeared to have not-so-good looking fins, and a little bit flakey, definitely frail. However, he recovered and started to look better. Now, he's back to where he was. Literally laying on the gravel (still moving the tiniest bit though!). I just fed my fish and, surprisingly, he came up to eat. So, any suggestions as to what I should do? Want to help him, but don't want this to continue, obviously. I have a 20g freshwater tank, all conditions I'm pretty sure are normal, because my red wag platy, sunset platy, dalmation molly, and other lyretail are all doing perfectly fine. I also have 4 baby platies that are doing great. One more thing- my three mollies (all boys) are fighting frequently, ugh, bad boys... could he keep getting injured from fights? thanks so much for responses!