growth rate livebearers [sec=unclassified]

Question
Hi Chris,
I have been keeping tropical fish for about 18 months now and have 5 tanks of various sizes lus another couple for breeding. I have recently started with livebearer breeding -mainly because I have been buying pregnant fish. I have 4 platy babies about 10 weeks old (looks like 3 are male)7 silver molly babies about 10 weeeks old(pretty sure they are sailfin) 12 or so swordtail babies 6 days old  (I think theyre swordtails) and one balloon/sailfin baby 3 or 4 weeks old. All seem to be doing fine. swordtails are in a plastic breeder box in a different tank - what is growth rate of  these to sexual maturity , when can you determine sex. The other babies are all together currently in a 15 gal tank. platies are a bit bigger than mollies. i give them a variety of food and they are very friendly. do you know the growth rate to maturity for both species, also same for balloon molly.
Is there any easy way to determine difference between female mollies, swords and platies

Answer
Hi Ken;

Once swords, mollies and platies are about 3 to 4 months old the males become quite evident by their pointed anal fins. They become sexually mature at 3 to 6 months. They grow at different rates so growth and maturity is very dependent upon water conditions, feeding, water temperature, population of the tank, genetics, future adult size, etc, so there really isn't a specific 'growth rate' estimation I can give you. Even if you gave me all the information about all these factors I just couldn't do it. You will just have to watch them and determine their sex when they are ready to, um, "show you". ;-)

As far as determining between females, if you are talking about whether they are females for sure or are underdeveloped males, you just have to wait and see. If you mean "which ones are the swords, the mollies or the platies", you have to look at body, tail, eye and mouth shapes as well as color patterns normally seen on each type. Do an Internet image search on females of each type and compare yours. Once they get to be large enough you should be able to tell.

Good luck with those little guys and gals!

At Your Service;
Chris Robbins