Hi!

We've recently gotten some mollies, and I have a few questions.

We have a 33gal tank that's been running now for almost 6 months. Lots of live plants.

Current population is a cherry barb, half a dozen neons and 4 mollies. Not sure if their colouring makes a difference, but there's one bright orange, one pure white, one dalmation and one that's a kind of brown with white "freckles".

First, I'm wondering how to tell whether they're male or female? I asked the fish guy to try and get some of each, but I wasn't really paying attention when he told me what they are because I had 3 kids with me at the time I'm not particularly interested in breeding them on purpose, as we don't have a separate tank or anything to stop any babies from getting eaten :( but if they get pregnant, I'd like to know how to tell so the kids can experience the process.

Second, is it normal for mollies to swim straight up and down? I've tried to do some googling, and have seen "swim bladder" thrown about, but always with the fish swimming nose down. Mine seem to do a strange nose up swimming. They'll all do it for a second here and there, but the dalmation will hold itself like that for a full minute or more. Even more oddly, it usually does this in the early evening, shortly after I turn the tank lights on. They otherwise seem healthy, swimming together, eating ok.

Lastly, and I suspect this is fairly normal around fish, but I've honestly never had a fish do this before. The orange molly quite often will splash around at the top of the tank. It'll be swimming around like normal, then suddenly spaz out and start flopping/jumping/splashing (?) around at the top of the water. It's quite comical to watch, actually. Just not sure if they're supposed to act like that?

Thanks so much for any input, guys!

Male mollies have an anal fin at its bottom. The females, particularly when pregnant, have a wider \_/ shaped bottom as against to a \/ shaped bottom that males have. The females take about 1 to 2 months for them to give fry after they become pregnant. Their bellies keep growing gradually.

Mollies wont specifically swim to the top and the bottom nor do they splash out of water unless they have:

1. trouble with water
2. recently delivered

I had a molly that gave 10 babies and it showed both the signs you said - going up and down and splashing but it died in just 4 days. Mollies get hungry a lot after they delivered.

Color of the mollies donsen't matter though similar color ones help. I had my silver marble colored molly deliver about 50 babies last week in which, almost all of them are dual colored - marble/black colored, purely marble colored and even orange/marble colored.

I recommend a frequent water changes to the extent possible. A partial 10% water cycle every day is what i would do in ur case. Also, observe if they are too hungry and how quickly they eat all its food.

Thanks for your reply, webgeek Between your description, and a photo I found showing the different bottom fins, I'm pretty sure we have 4 males. Guess the fish guy didn't know the difference as well as he thought. We'll have to get some females when we add fish in a couple of weeks.

Turns out we had an ich problem starting, so we've treated for that during our last cleaning/water change, and so far there's been no more splashing around from our orange molly. So maybe he was stressed out because of that. I appreciate your insights!

Unlike what most people think, frequent water changes actually help these fish. I do partial water changes to one or the other 4 of my tanks every day. About an hr spent on these stuff every day. phew.

I do not like adding more females coz sooner or later once you start getting babies, one or the other fish will be pregnant and you will be forced to upgrade your aquarium. Even one female is enough to build a school of these fish.