how do i know if my black mollie is pregnant and should i be moveing her to a seperate tank

Question
QUESTION: So let me start at the beginning, i recently acquired a 35 ish gallon tank from a friend of mine.  It came with all the stuff for it i.e filter, heater, gravel etc.  i removed most of the smaller fish like some tetras and smaller Mollies  and put them in a different tank that i set up at my little girls school. I however kept the biggest Mollies and a 6-8 inch placostimus as they were way to big for the tank at my little girls school.  After I removed the smaller fish the big black Mollie had babies. I then moved that tank to my house set it up and transferred the big black Mollie and the placo back into the tank,and keeping the babies in a separate tank. i also added a couple more Mollies and some cherry barbs some runny nose tetra's ,neon tetra's and a couple platies (i think thats what they were called). so far all the fish have taken very well to the tank and all the water test are normal  but i am concerned about the black Mollie as she is behaving odd she is still active and eating  but when she is active she is being harassed by the male sail fin Mollies that i addend so she seems to be prone to hanging out on the bottom allot and wiggling around.  i think the black Mollie may be pregnant and for this reason i believe the sail fin Mollie wont leave her alone. could she be pregnant and should i move her to separate tank till she has her fry and then put her back in the community tank. if she does have fry how do i take care of them cause all but one of her last batch died. do i need a filter and a heater, and should i use a light. everything i have read says use live plants but are fake plant ok. and when is a good time to introduce the baby Mollies back into the tank if i want to keep them i assume at very least they should be bigger than any fish in the tanks mouth. but i want to be sure.

ANSWER: Hi Cameron,

I can give you great advice for breeding Mollies.  I raise them, myself.

Add at least a teaspoon of marine salt per gallon to any molly tank.  Usually a regular fish can live fine in 1 teaspoon of salt per gallon and it enhances the lifespan of the molly to do so, so it's advisable.  Also, fry survive in a higher rate.

The fry tank needs salt also.  Mollies are brackish water fishes.  Not freshwater (as the petstores would have us believe).

Fry will live far longer in salted water.  They also require a constant heat of 80F.  They require filtration and for fry, I use a HOB filter with a sponge over the suction tube.  This prevents babies being sucked in.

3 gallons to 5 gallons is fine for the fry.

The parents will breed often and have babies every couple months.  Baby mollies need crushed up fish food to eat...flakes are fine.

Lighting is always recommended for fish.

1" babies before putting them into the main tank.  The fish will eat them, otherwise.

I would isolate the mother in the fry tank only when she's ready to give birth.  Let her be in the community tank meantime.

I hope this helped you out and thank you so much for asking.

Happy fish-keeping.


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QUESTION: Thank you for getting back to me so soon the info you have provided is great. but I am still curious what if any sign i should be looking for that she may be ready to pop so i can move her at the appropriate time and not to soon. should i be worried about her behavior with regard to her constantly wanting to be on the bottom. i think this is her way of avoiding the constant harassment of the male Mollie who i guess really wants to mate with her, but I'm not quite sure.

Answer
Hi again,

Constantly sitting at the bottom is also a sign that Nitrites and Ammonia are too high in water, in fact, it is the first sign of nitrite poisoning, so I'd really like you to change 50% of the water and 25% every weekend for a month to get the parameters back in order.  Nothing like sparkling clean water for babies.

Please, also thoroughly clean the filter. :)

When my females are ready, they will go to an upper tank corner and hover.  They will seek out a spot hidden such as one above plants.  They will often begin running the glass while in labor, stopping periodically or flitting and babies just fall out at that point.  Each female seems to be different, but just prior to birthing, their bloated stomach looks to me like it's about to burst, and their vent has a bump, inside it, as if it's swelling open a bit.  It goes from black (where the normal hole would be) to swollen a bit with some pink showing.

It looks like an opening about to birth.  The spread back there is a sign, but it's very subtle and only trained eyes observe it in most cases.

Good luck!  I hope for many babies!