Baby platy, help!

[Susan Anvin]

I bought 2 platys that have the right bottom fins to indicate they are female on or around Sept 24. Today cleaning the tank I saw one baby platy, probably about 3/4 inch long. Completely left alone by the other fish. The store I got them from did NOT sort their tanks by gender so taking home a pregnant fish was a very real possibility... But it seems too long a time between Sept 24 and now for this to have been the case. How long do platys carry young and how long would it take for the baby that lived to get to that size?

 

[Roden]

Platies carry sperm for 6-12 months after last contact with a male and give birth to 50-100 fry every month. The only times they don’t give birth every month is when they are stressed and in bad conditions, in those cases they may withhold giving birth until better conditions arise.

I’m honestly surprised this is the first fry you’ve noticed. They do typically get eaten, but so many are born there are usually a few survivors you will see. Guess this little guy was just a really good hider!

As for how long it’d take for him to get that big, likely around a month, give or take a week.

 

[Colin_T]

Baby platies are less than 1/4 inch long when born so a fish that is 3/4 inch long is probably a couple of months old.

If you have lots of plants in the tank it gives the babies more places to hide and you get more surviving.

Female livebearers (platies, mollies, swordtails, guppies) can carry up to 6 sperm packets from mating with males. They use 1 sperm packet to fertilise each batch of eggs. The gestation period is about 1 month, where the eggs take about 1 week to hatch and then the mother carries the babies in her body for another 3 weeks while they develop. After 1 month (give or take a few days) the female gives birth to free swimming baby fish. The female usually hides among plants when in labour and the babies hide in plants straight after they are born.

 

[Susan Anvin]

So the summary is yes, this very likely is a fry from when Candy was in the pet store tank. It's been 3.5 months. So maybe she was still stressed from the move the first month and didn't use any of her stored sperm packets? And I guess I'm hearing I could get more fry.

I'll know for sure when she's bigger but the fry looks female. The fins are tiny, translucent and she's never still so it's hard to be sure. I am naming her Harriet Potter, the Fish Who Lived.

I have no idea how I missed seeing other fry or indeed missed seeing HER for a month. I siphon a fraction of the water weekly and spend time watching them when they eat. I also don't know what the poor dear had been eating... I've switched from pellets to flakes so I know she can eat some of the food. The other fish seem to largely ignore her, so I'm just gonna let her hang in the tank.

But am I really likely to get more fry?

 

[Colin_T]

How often do you do water changes and how much water do you change?
Do you gravel clean the substrate when you do a water change?

Small water changes don't do anything to help keep a tank clean. You want to do a 75% water change and gravel clean the substrate each week to help keep the nutrients and microscopic organisms in the water at low levels.
Make sure any new water is free of chlorine/ chloramine before it is added to the tank.

----------------------
As mentioned above, female livebearers carry up to 6 sperm packets from previous matings. This means females can have a batch of young every month for up to 6 months after they bred, even if there are no males in the tank.

If you have lots of plants in the tank, more young will survive. The best plant for livebearers is Water Sprite (Ceratopteris thalictroides/ cornuta). It is a floating plant with lots of roots and leaves for the mother and fry (baby fish) to hide in, and it grows rapidly. If you get too much it can be planted in the substrate where it grows into a lovely light green shrub.

 

[Susan Anvin]

I do a 25% water change weekly with a gravel vacuum. Thisis actually already dramatically more than its advised by the pet store and every single platy/molly care website or book I've ever read, but it seems to work a bit better given my tank is pretty small. I use a water conditioner and also use the bacteria starter drops at what the bottle recommends for new water in established tanks. Fish seem content? Changing water that much would SERIOUSLY stress them out not to mention completely destroying the bacteria balance. What you're recommending would probably kill most fish.....

 

[Susan Anvin]

And I have 4 fake plants. I wasn't intending to have young so didn't decorate with that in mind. There's a reason I have an all female tank

 

[Essjay]

but the fry looks female

All livebearer fry look female until puberty. Then anal fin of the male fry changes shape. Your fry probably has more growing to do yet before it reaches puberty.


Never believe anything a fish shop says, 25% water changes are not big enough. And books can become out of date very quickly. Nowadays we recommend at least 50% every week.

 

[Roden]

25% waterchange can be large enough dependent on how your tank is. Each tank is different and some don’t even require weekly waterchanges to remain healthy. This being said going up to 50, or even 80% will not harm your fish. Just temp match and pretreat the water if your using buckets or if you’re using a system like the python treat for the quantity of the whole tank.

Although I am a bit confused how this topic came about lol.

As for it you’ll have more, yes, you likely will. But I wouldn’t be to concerned about it considering you haven’t seen any but her. They can continue to give birth to up to a year if they give birth every month, so you are looking at a potentional of 8.5 months of pregnancy left.

If you don’t want fry don’t put any decorations or plants floating at the top, as the fry will typically fry and find shelter towards the top.