mollies, swordtails - not seen much here?

driftwoodhunter said:

How do you tell mollies and platies apart? Are there distinct differences in physical traits like mouth shape or fin shape? Not sure I want to get any after all, but I'd like to be better able to identify these fish when my lfs lists the tank's inhabitants as mollie/platy. Which is which? I don't trust the store's employees to know!

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It's actually pretty easy once you see them together! And I can't find any pictures of them together to show you.

Platies tend to stay smaller-- I've never seen them get bigger than 2 inches, while mollies can get HUGE. Platies are shorter, with rounder bellies, while mollies tend to be much longer/sleeker. Mollies also have huuuuge mouths. If you ever get the opportunity to look down at them from the surface, they tend to come to the surface a lot to breath and boy do they have big mouths (mollies are also a lot more likely to follow you than a platy, but I mostly see it in outdoor ponds/my own tank, so can't say about your LFS). Since they both come in a wide array of fin-shapes it's kind of hard to describe them based on those differences. Mollies tend to be called "sailfin" and platies "hi-fin."

You might also be able to tell from the varieties: platies tend to come in red wag, tuxedo, and panda, while mollies will be black, silver, dalmatian, or pineapple. I have never seen a molly as bright orange as a red wag. If it's as orange as a traffic cone with black fins, it's a platy (or swordtail, but I'm gonna guess you can spot a swordtail).

You might also see mickey mouse platies. AFAIK mollies don't get the mickey mouse mark at the base of the tail.

There are a lot of other platy varieties, but those are the ones you're almost guaranteed to see. Trust me, once you really see them in person you won't confuse the adults.

Mollies

Platies

Hey driftwood. Long time no talk.

I may be able to help with your livebearer conundrum. Most people don't have them. In my experience, they are short lived and can be aggressive toward each other. They are prolific breeders and that causes male/female aggression. They are also territorial and that causes male/male and female/female aggression. They can be kept in a community tank, but with some caution. I have swordtails in my 20 high at the moment, and I can't wait to get rid of them. They are a menace. They try to eat everything. They are pretty and can work well in a larger tank IMO. Guppies are pretty much the same way. Only a little bit smaller unless you get a true Moscow strain. They are eating machines too. I have seen them munch on plants, and even other fish. They are also notoriously cannibalistic and will eat their own young minutes after having them. They are more of a challenge then people think and their average lifespan is only a couple of years. Not worth it to me. As for mollies and platys, I don't have any experience with those, but I would imagine they are along the same lines. Mollies, from what I hear and have read, do better in brackish water and can be even acclimated to live in a full on salt water tank. As far as putting something in a 29 gallon tank, I think you would only get away with a trio of 1 male and 2 female. Maybe a couple more for guppies. But it is also a good idea to have 2 females to every one male. It will help disperse all the aggression a bit.

Hope this helps, and if I am wrong, someone let me know please. Lol.

My grandmother kept swordtails and mollies together for an eternity--late 70s, early '80s. Although I tried it many times over, I do not have the hand for Mollies.

Although I concur that swordtails eat anything and everything they encounter, they are wonderful fish. I have only 3, an enormous female, a tiny male and tiny female. They have worked out wonderfully with both types of common platies (maculatus and variatus). I had my concerns, as variatus and sword tail males are known to fight. I have one male of each species and they don't even acknowledge each other.

The only issue is with that largest female swordtail, who eats her own and the platy young as soon as she sees them. That is not an issue for me because it keeps my population managable. I also think the size of the male creates the largest challenge. Anytime I have opted for a "runt" or smaller male, the tank has gone well, especially if at least one of the females is much larger than him. There tends to be less aggression, though I am going on anecdote and historical memory.

After having avoided all livebearers since 2007, I am in love again. I started out with these guys and think they'll be a mainstay for me in the future.

My grandmother's recipe for swordtails and mollies was the addition of salt, hard water (as folks have discussed) and plenty of room. She'd keep a single male and 3-4 females. She usually had a few more mollies, with less attention to sex ratio. She only kept the smaller mollies, never going for the sailfins. Her tank was some of the healthiest I've seen.