Concerned about platy sterilization...

[JamesB]

I have had my 10 gallon platy aquarium stocked for about 2 months now. The latest of the 10 occupants were added about a month ago. The tank was cycled before the first fish went in and I've had only very minor amonia spikes when adding pairs of occupants, otherwise amonia and nitrites have remained below .25ppm at every check. My nitrate level is never allowed to rise above 20ppm, but I have some live plants in the tank so I usually don't sweat it much at all before that point.

I have maintained the water temperature at a minimum of 78 degrees, though the room the aquarium is in does get hot sometimes during the day and the temperature spiked up to 82 degrees during the hottest part of the day on some of the hotter days in July.

My concern is that despite picking females that I was fairly certain were gravid at the store when bringing them home I have yet to see a single fry. There are 6 females and 4 males, no one seems harassed or stressed. They all display wonderfully and you can see them playing with eachother in the relatively strong current from the oversized power filter I use. None of them show any signs at present of being gravid nor have I seen any such signs in the past two months that weren't there at the store when they were purchased.

Any thoughts as to why I'm not having fry yet, possible explanations I can look for, etc?

[Ringo]

There may all just be getting eaten, seeings how you have 10 fish in a 10G tank.
Soon you are gonna need a bigger tank. do you plan on upgrading soon? if you do a minimum tank size should be 20G (for that amount of fish)

what kind of plants do you have in the tank? If you don't have Java moss (and you want fry) I suggest you get some
The fry will hide in there until they are big enough to go out on there own, but still quite a few will get eaten with that many fish in that size tank. And fry arent exactly the brightest of all fish, lol

and btw, Welcome to the forums!

[JamesB]

At first I thought it was a bit crowded too, but 4 of my 10 fish are 'rescued' so it couldn't really be helped. A larger aquarium will happen eventually, but for the moment I had figured that since at least one of the females should be ready to drop at pretty much any given time that I could transplant the one(s) near delivery to an already developed 5 gallon, then back to the 10. It's not a perfect system but the amount of space that I have in my apartment is limited and short of sending the fish off to someplace where I don't know how well they'll be treated ... meh.

In terms of care, though, they do have a 150gph biowheel filter (even sponges take up too much room IMHO) that they love to play in the flow from. Their chemical levels are closely monitored with tests at least once a week but normally twice, and they get at least 2 gallons of water swapped out every Thursday, a little extra if the nitrate levels approach 20ppm.

I have 2 java moss, a moneywort and a cabomba--carolina (just identified thanks to the forums!) growing along with a couple of pieces of dead coral and some nice beard algae that I picked up. I'll put up some pictures later. The eating thing would explain it away, I suppose, except that I would think at some point with all those females I"d have seen at least one fry moving around somewhere before he got scarfed. The fish are kept pretty well fed (flakes once per day, dried tubifex once a week and dried seaweed once a week) I think, so I wouldn't think they'd go after the fry as soon as they drop?

Aside from not having seen a single one, though, I haven't seen any gravid spots since I brought known pregnant fish home from the store. I accept that a good portion of store wrought pregnancies won't come to term due to the stress of the move and the new environment but I'm really starting to wonder about this aquarium...

[Damon]

If there are no safe places for your females to release their fry, they wont until the last possible moment. They have to feel safe to have fry.

[Dabaers]

Isnt the gestation for platys about 8 weeks? Or is that just mollies?

Kath

[JamesB]

Had read that gestation for the first batch released by a female could take 6 weeks and that after that they're normally 4-5.. but then, I wasn't really reading for breeding information at the time. I just figured that after two months I'd have seen something.

In terms of the fish feeling safe, I suppose no one but the fish can tell us that. There is plenty of cover in the aquarium as it sits, though I have rearranged a few things the past couple of weeks trying to maintain cover and foilage without sacrificing swimming room. I did have to wind up pulling the artificial cave and replace it with another smaller piece of dead coral to form a new little nook for hiding in due to space considerations... and color schemes, but that was done just yesterday.

I suppose I'll just keep them alive and happy for a couple more months, if I don't see anything by then I suppose I'll know for sure that something's wrong.

This brings up another question, what does mating behavoir actually look like? I've observed the aquarium pretty much all hours of the day and night and I have yet to see anything other than what I would describe as courtship behavior. I don't think any of the females get harassed per say, but I have seen kind of a follow the leader type game between a male and female a few times, but it never ended in anything that would allow for copulation that I could see... Is it a pretty instant process or is there some visible 'action' that occurs?