Is it possible that goodeids can synchronize birthing? My Xenotoca eiseni trio were all added to the tank at the same time (male/two females) and both the females gave birth the same exact night. Is this just a lucky coincidence or is it possible that hormonally they became in sync and gave birth at the same time because of that? It would make possible sense to have multiple females giving birth at the same time so that more young would be born during times of excess food or to overload possible predators by numbers. I dunno just kind of guessing but I haven't noticed this happen that often with my other fish and this has happened a few times with my goodeids.

I have to admit, even when i had 50 tanks, getting two species drop they fry on the same day was rare, let alone 2 the same species at the same time.

But that's great news and enjoy them.

I figured its nothing but it would be interesting to see how much of an effect hormones would have on the other fish in the tank. It wouldn't be completely out of the question. Humans are effected by each other hormones and I would guess it would be easier for fish because there is the water to conduct the hormones to each other.

So you gonna set up an experiment? no idea how to go about it though

It would be difficult I think to really experiment and prove it. If it was a similar hormonal response to what some women go through where they can synchronize their menstruation then it would be possible to try keeping some females together without any males then introduce them to males. Maybe try a couple with each male in several tanks and then a few single females with single males and see how it goes? I dunno, thats just an idea I came up with. Any other suggestions?

Good if you have enough space. i know i don't sadly.

I don't right now, I have too many fry tanks going with different species. Its breeding season for me (and of course the fish LOL). I will have to remember this for the winter when I par down my breeding.