Livebearing hybrids

Question
Hi Chris.I have Mollies,Platies,Swordtails,and 2 Albino Corydoras in an established tank(0 ppm ammonia,12 ppm/- nitrates).I would like to know a couple of things if possible.Can Mollies cross with Platies or Swordtails? I have a Gold Dust Molly and he looks more like a Platy(same kind of dorsal fin)than a Molly.I just got the Gold Dust Molly 2 days ago(he's young,3/4 of an inch long) and he was all over the Platies and Swordtails(doing the gonopodium thing).My male Platies still chase him around.I know there is a hierarchy between male Platies and even male Swordtails,but they usually ignore Mollies.I have a typicle white male Molly who ignores the Gold Dust Guy altogether.Also,I purchased a Swordtail/Molly hybrid(that was what the petstore called him) a while ago from the petstore,but I have people saying that is impossible because those species don't cross.When I say cross,I do mean create a viable offspring.This is my swordtail[ s146.photobucket.com/albums/r252/Amidicus/ ]can you tell me what type he is?He is 3.75 inches mouth to tip of tail.BTW,I had purchased a female from the same tank/brood a week prior to buying the one in the picture,and she had the same color scheme as the guy in the picture,but had the body(dorsal fin,overall size,appearance)of an adult white/silver Molly female.I thought it was a Molly and went back a week later for a male Molly only to find out that they were considered to be hybrids and purchased the male.All the fish in that tank looked like my male,or the female.The female died some time ago.Have I been hoaxed?Can those fish cross?Can a diluted Molly such as my Gold Dust Molly actually impregnate my Platies or Swordtail females?Please help!

Answer
Hi Ryan;

Swords and platies have been known to interbreed because they are more closely related to each other than mollies are with either of them. I don't know if mollies have actually been successfully hybridized with platies or swords, but I suppose it's possible. This gets into areas of breeding I know very little about. I have read that a high percentage of male hybrids are actually sterile though.

Yours looks like a typical male swordtail. It is a color I have seen for many years, but I don't know if it has a particular name. They usually came in shipments with a mixed group of "assorted swords". Here is a link to another one like your guy I found on a web site;

http://www.acquariofacile.it/pesci/foto_pesci/xiphophorus.jpg

For more information on hybrids you might try an internet search using the fishes' scientific names with the word "hybrid".

At Your Service;
Chris Robbins