Look for the dark "gravid spot"....the dark area in back of the stomach but in front of the anal fin in females. YOu will see that as a dark spot in young female fish even before the gonopodium (the pointed anal fin of the male) develops. Once you look at a batch of them closer it will become more obvious.

Hi
Are you line breeding or just separating to keep the nos down?? I line breed red eyed red swordtails and obviously have to keep a close watch on the sexes . The entire trait will disappear in one generation!!
I'm curious as to the possibility of sex change as no matter how close I monitor the offspring I still get some surprises lol. have heard of this in livebearers but can't find any further info. My understanding is that all livebearers are born sexless and change sex at maturity
Seems to hold to my own experience Any thoughts on this or know of further info?? thanks gary

We were just pondering what might be involved in line breeding.

garyfla-
I have seen those red eyed reds....awesome looking fish. I don't think the sesless thing holds true for guppies, although I know that is a "problem" with swordtails, even had female swords in my aquarium change. I know those late changers generally turn out to be the largest male swords, but I thought they might be sterile(?) although I don't know. In any case, young guppies are easy to separate based on that gravid spot in the young females...looking at a batch of them right now.

Hi
The last I heard the ultimate is "Red eyed red hifin lyretail with females also bearing swords lol. That's a bit TOO much selective breeding for me lol
I do like the RER but want Blood rather than cranberry or worse pink lol. Since they will not breed true always have to keep separate stock of albinos but still get a few lutinos. as well as greens .
Since I keep my stock in outdoor ponds ,impossible to keep track or them. The breeding stock is kept in aquariums.
Since red swords were created by crossing red platies with green swords you have to start with a intergenic cross so will never get 100 percent.
As to sex change I think I've seen this but if they switch from functional male to female have no idea.
I have noted the ratio of M?F can somewhat be controlled by the pH. higher producing more males. Very seldom is it 50/50 anyway.. Was hoping someone could direct me to some research on the se change issue You could raise the fish for centuriies and still never obseve this?? Thanks gary

Gary-
That is awesome. BTW, I have read articles of pH influencing sex of platies.....but I don't remember the source (one of the aquarium fish magazines, some time ago).

Hi
I recently bought a school of zebra danios for a 75 gallon plant tank . Two unidentified hitchikers came in the bag.. They appear to be female guppies and have grown from 1/4 to over an inch in less than a month. Feel confidant they were way too young to be pregnant when I got them but both appear to be really filling out.
If fry start appearing I'll certainly know something odd is going on. Since they both sure look like females and the only other fish are zebra danios and clown loaches.lol Will be interesting to see what happens Maybe I'll actually get to witness a sex change.??
gary

Hi
Have what appear to be two fry but was unable to catch them so suspect they will be eaten. Since they could only be guppies. How can that happen ?? I didn't know ANY vertabrate could reproduce assexually??
Even weirder than a functional sex chage don't you think ??lol gary