Yeah... I have a 100 gal tank in which I have my "adult" swordtails... then I have a 12.5 gal tank that houses my younger swordtails until they are big enough to put into the 100gal community tank. This tank has Killifish, so I don't want them to be picked on or eaten.
However not every young swordtail is one inch or less.. some a larger. But I'm allowing them to grow in this tank. Which is a long 12.5 gal tank, 9 swordtails in all in it. 4 are below an inch in size the other 5 are just over an inch in size.
I go to check on them one day, because out of no were Snails appeared in the tank, well I didn't see them before at least lol. Anyways I start poking around counting the fish to make sure non passed away. I was counting, and found more than 9 fish. This was surprising to me, as the adult fish have been out of that tank for over a week. I check on the tanks once a day. Haven't seen the fry before either.
However I have a low fry count, 4-8, so I might be wrong but one of my younger swordtails might have been prego. Or a larger one gave birth and they just were hiding. I have a lot of hiding places for fry in this tank.
I put the adults into the community tank so fry will be eatin to stop over population on swordtails (before fry I had 20 ish). When I say adults I mean the size of giant danio's. Some larger.
I'm excited for the fry, lol just wasn't expecting it.
Oh also found out, I have betta fry as well lol however only have 4.