Babies Or Not..

[Fish are friends]

I have 3 mature black mollies in my smallest tank, (5gal) i have suspected the one is pregnant but not 100% sure and i want to know if her behavior changes just before she gives birth.. she is swimming very erraticly and staying in the corners and the male wont leave her alone...

 

[OldMan47]

Indeed, an almost ready female exhibits strange behavior FAF. That does not relieve you of observing the actions of your own fish though. Many of us have observed some very different things as our fish approach full term. Unless you can say, with no reservations, that your fish are in similar conditions, anything we might say here is immaterial.
If you can provide a picture of your present female, we may be able to help you interpret her present state. It does not guarantee an answer but may give you a better understanding of where you are in your tank.
A thorough description of your female's actions may also help us interpret the fish's actions for you.

 

[Fish are friends]

I have a few pic i will add... I cant see a fattening of her abdomen, its just her behaviour and the fact the male wont leave her alone. i googled her behaviour (the way she swims) and it might be something like a swim bladder infection but these are all guesses.

She will swim normally for a while then she will do all sorts of acrobatics and then just sit in the corner like that... my first assumption was that she was expecting...

 

[Fish are friends]

Just wondering if anyone can shed som light on my mollys behaviour... she now swims normally but spends most of her time on top of the filter. I thought she might be pregnant but now i dont think so.. i guess i am concerned about her...

 

[OldMan47]

If she is resting most of the time on top of the filter she is almost ready to drop of has another problem. After about a week, I am going to guess it is another problem.
It is time to check your water parameters. Mollies have the exact same issues with an immature tank as any other fish. They do not do well if either ammonia or nitrites rise above about 0.25 ppm as measured by a liquid test kit. If you find either of those chemicals present, do a huge water change of at lest 50% to bring it down.
If you find that part of your chemistry is OK, the next thing to look at is the hardness of your water. Mollies do not generally do well in pure water. Common pet shop mollies require a rather high mineral content in their water. If you have "ideal" water of a neutral pH and low mineral content, it will be stressing your mollies. Plenty of egg layers do great in that kind of water but mollies demand a higher mineral content. Depending on what fish share the tank with the molly, you may or may not be safe raising the mineral content. A simple way to raise it and improve a typical molly's health is by adding some crushed shells or crushed coral to the filter's water flow path. A tiny bit of the calcium carbonate that makes up those materials will dissolve in your water and raise the pH and mineral content a fair amount. The problem with doing that is that low mineral content water really is best for many other fish such as angels, tetras and even plecos which will not appreciate any such change in their water.

 

[Fish are friends]

The tank that has got 3 mature mollies and 2 youngish fry (well they look like fish already so not so young) Its only the one that is acting wierd, the rest seem pretty normal. i regularly check the water and keep the levels as low as possible. they dont seem to rise too high and i do a 30% water change once a week.

She has started swimming with a twisting motion in her tail like she has a kink in it and i think her abdomen is swollen but its hard to see cause she is always hiding. As for the water, i live in a hard water area so there is plenty of mineral content. i guess waiting is all i can do at the present moment.

 

[OldMan47]

One last suggestion is to make sure the diet you have your mollies on is one high in vegetable content. About half of what I feed my mollies is food meant for plecos. The other half is typical tropical fish food. The addition of the vegetable foods seems to help them thrive.