View Full Version : Platy fry growth and scoliosis

10-18-2006, 12:50 PM
Hello! I am trying to find out the growth rate of platy fry - specifically....how long does it take for platy fry to "grow-up" or reach adult size????? Only 2 of my platy fry survived and they are about 8 months old now and very small....the large one is maybe 3/4 inch long and the other is about 1/2 inch. That doesn't sound super small, but when you see them, you realize how tiny they really are. Coincidentally, the large one had what I would call scoliosis. Her whole body is kind of shaped like an "S" - but she gets along just fine and seems to enjoy her life.Anyways, I would appreciate any thoughts you all may have on this size issue! I should point out that the fish with scoliosis was born that way, so I think it's a genetic problem....the little, tiny fish - well I just don't know! She eats great and seems to enjoy herself, always exploring. Jen

10-18-2006, 3:24 PM
I'm interested to hear what you find out about this as well...I have a single fry (the only one I found) that has been in a 2 gallon for about 3 months, and is maybe 3/4" long, but definitely still to small to go in with other fish I think. I believe it is a dwarf platy, but it could be a molly as well. I fed it the "First Bites" fish food for about 2 months, and now she is eating regular flake food ALL the time- I feed her about 3 times per day, and she is still super small. I read something about doing more water changes to remove the growth inhibiting hormone they give off, but I haven't noticed much of a difference.

10-18-2006, 11:28 PM
I'm not really sure how long it's supposed to take, since I've only ever had one baby survive long enough to become too large to eat. She's probably about eight months old now, and still hasn't reached her full adult size. If I were to hazard a guess, I would say she's about an inch or so long, but I'm a terrible estimater for lengths and more used to the metric system. >_>

10-18-2006, 11:36 PM
They grow faster in a larger tank vs. say, a breeder trap. My molly fry that were in the a regular tank grew to 1 inch in 1-2 months. In the trap, it was like 4 months to get to that size. Platies and fry are a little smaller than mollies but I expect similar growth rates.

I've read that due to inbreeding, a lot of livebearers have genetic problems causing curved spines. Some live a couple years, others don't see adulthood. The curved spines could sometimes be confused with fish tuberculosis.

10-19-2006, 6:32 AM
Commercial breeding operations are mainly concerned with color, and usually don't keep records on which parents produce defects. You can't really expect that with large-scale pond breeding.

I also suspect that most store fish get mixed up with other colorways on the way to the store. Either they throw all different colors of fry into one big grow-out pond and sort and grade them after, or they get mixed up at the wholesaler. The first fry batches often look like they've been crossed with some other male. I would guess that commercial breeding is pretty cutthroat, and that most store buyers consider livebearers to be a bulk item and are more concerned with cost than quality. If they dedicated more time and care to the fish they'd go out of business.

10-19-2006, 7:13 AM
My girlfriend loves her platies and she had a trap and cought a heap so I opted to take home about a dozen of them to raise for her in a spare tank I had. I think it is about a 10G. Anyway, I am just trying to remember how long it took. I reckon I put the fry in the new tank at the start of this year. At about 4 months I think I put them in my 30G community tank. At that stage they were at a size that my angels couldn't fit them in their mouths. As soon as they got in this tank they went on a huge growth spurt and were about 3/4 grown compared to a full sized adult. Then I gave some back to my g/f and some to her friends. I kept a few and they quickly grew to adults within the next month. However, my g/f and her friends had a smaller tank and their fish have never grown to the size of mine. I also bought two platies, the same size and colour, I think they are brother and sister, I kept one and gave one to my g/f. They were about 1/2 grown when i got them. Mine grew to full size and my g/f's didn't grow much more at all. Her tank was about a 10G.

Basically, if you have a tank that is less than 20-30G then I don't think platies or any fish realy will grow to their full size. No matter how long you wait or how much you feed them or how many water changes.

In a 30G+ tank they should be fully grown in 6 months I think. 3-4 months in a smaller fry raising tank perhaps and then a couple of months in a large tank to mature and grow out.

10-23-2006, 10:28 PM
My pair of platies had about 50 offspring this past year. Some of the fry grew out in a small tank, others stayed in the 55 gal. community tank. I didn't notice any growth difference, but I didn't measure. I'd guess they reached 2/3 adult size in 3 months, and puberty would set in, which made some of them edgy and annoying to the other fish, so off to the store they'd go.

Out of those 50 there were two with bent spines as you described, and two others that just didn't grow at the rate of their siblings. Those two are not only small, but they prefer to sit on the bottom unless it's feeding time, and their bodies don't have the usual arched back and belly... they are more rectangular. One of those was a 3rd generation "accident" (I do separate the boys from the girls as soon as I can tell which they are).

My platy parents were from different tanks and were different colors. Since platy ladies store sperm for months, it was not surprising that most of the first few batches looked more like the mother's former tankmates than the dad.

It's a soap opera in there! Who needs TV?

10-31-2006, 7:00 AM
It's a soap opera in there! Who needs TV?

That's what I always say about my aquarium! It is just like a soap opera. Dwarf cichlids are the best for it imo.

10-31-2006, 8:27 AM
Platies compared to other species of livebearers are slower growing. Their bodies are squatter, their bodies nowhere near as long as swordtails, mollies and guppies and so their growth appears slower. I rear platy fry in with similar aged guppy fry and whilst the guppies reach sexual maturity at over one and a half inches long at 3 months and will give birth the platies are only three quarters the size and mature much slower.
Their diet here also makes a big difference. At birth mine are fed liquifry and microflakes 4 times a day. A better feed would be newly hatched brine shrimp if you can get it. Then I add live foods into their diet three times a week (bloodworm and freeze dried daphnia and tubifex) from 4-6 weeks old depending on growth.
I dont think tank size matters so much but i think warm temperatures of 78-80 degrees also helps as does good water circulation which helps them to grow stronger.

10-31-2006, 9:51 AM
Hi thedogzoo,

I bred platies before when I was young, then I shifted to swordtails. Anyway, platies and swordtails belong to the same genus, Xiphophorus. Based on my experience, my swordtails reach their adult size at 1.5 inches or more (females grow faster than males) approximately within four months. By the fifth month, females start giving birth to few fries. There is an increment in the number of fries on the following spawn. With regards to deformities, I agree that there's a possibility that they inherited it from the genes. Anyway, they're active and happy so you don't have to worry much. ;)

I found platies more hardier, faster to grow/mature, and easier to maintain/breed than swordtails. This information is just a close estimate for comparing some of the characteristics between the two.

Thanks and good luck!

(My experience serves as my basis for the information I have mentioned above. I hope it would help even in a little way. Again, thanks... :) )