I bought some platies (5, 1 died, now have 4). When I got them, the subject of sex never crossed my mind. I'd assumed it would be like the guppies I used to have, that you'd just get boys unless you asked for a female to breed with. From what I've been reading, that doesn't seem to be the case and I could end up with babies if I've been given female fish.
I've looked at the pictures as to how to tell them apart and it looks like I could have 2 males and 2 females. It's pretty hard to tell. One definitely looks like a female (fan-shaped fin), one definitely looks like a male (pointy fin), one likes to swim really fast with his fins up against his body, but when I got a look, it looked like a pointy fin. The other one is a very pale yellow fish, so it's difficult to see the fins at all because they are transparent, but I think it could be female.
Do they normally just give you any old mix of sexes without warning you? (I could be worrying about nothing if they do routinely give you all the same sex.)
I'm worrying about the little yellow fish. He/she isn't joining in with the others and is spending most of the time down in the bottom corner of the tank where the filter inlet is. She (I'll call her "she") does come out sometimes but goes back there on her own. She's not doing anything else that makes her look sick. It's a new tank, but there's a nil ammonia reading at the moment, it hasn't started to go up yet.
If she is a female, could she be hiding because she's scared of the "men"? The other three fish are all bigger in size than she is, would that make her fearful? When she does come out, none of them seems to be chasing her or giving her a hard time. If I do have males and females, the information says to have more females than males. I'm not that keen on getting lots of females because I'll be overrun with babies with nowhere to put them other than in the fishes' stomachs. Is there a way of approaching this to end up eventually with all one sex by natural attrition? Would having all one or the other be peaceful? If they breed will all of the babies just get eaten?
Are there any innocuous reasons for a fish to hide away, or does it definitely mean that she is sick or stressed?
I'd be grateful for any advice. Thanks.