Is my Platy pregnant? - Page 2 - Tropical Fish Keeping - Aquarium fish care and resources
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post #11 of 11 Old 01-14-2008, 04:01 PM
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Originally Posted by babybackriib
Dawn, I am so glad you responded to my initial post! You have been so helpful and informative, I hope you don't mind helping me out a little more!
I never mind helping! Ask away!

I have a 16 gallon bow front with 5 fish already. I know the worst case scenario is 1 fish per gallon of water, but I also know that the more fish you have, the more waste there is (that's why I had 5 fish in a 16 gallon tank).
It seems you have been confused with the 1 inch rule. The way that should read is "1 inch of adult fish per gallon of water", and this does not apply in all cases. Things like a jack dempsey that reaches 8 - 10 inches surely can't survive in a 10 gallon tank (and still be healthy). Whenever you buy a fish you need to know how big it can get. With your platys you are looking at about 3 - 4 inches each (on average, though I have seen platys up to 5 - 6 inches) fish when its full grown. If you take the average number of 3 inches each, multiply that by 5 for the number of fish in the tank, and you come out with 15 inches of fish in a 16 gallon tank. That is about the limit for a system of that size. This is why I warned about the fry in the tank. After just a few wks those fry are going to be big enough to contribute a great deal of waste to the tank. To know what size tank that number of fry will need, do the same math calculation. 14 fry x 3 inches each = 42 inches of adult fish, so 42 gallon minimum for tank size. Livebearing fish can be a challenge to keep due to their breeding habits. Quite often when I've sold platys to a customer I have had to ask if they intend to upgrade to a larger tank within 1 - 2 months... if they say no, I will usually discuss with them the benefits of keeping only male fish of that species together to avoid breeding and overpopulation problems. Any female fish coming from a store tank has to be expected to be pregnant, and due to their ability to retain sperm in the body for a very very long time, 1 female livebearer can be expected to have up to 4 spawns without ever having a male in her tank. If you get through about the first 4 months with a female, you can pretty much count on that she is done and not pregnant.
When I purchase breeding stock, my females are always seperated from all males for at least the first 5 months, to be sure that the fish I'm mixing are the fry I'm getting. This gets to be important when breeding for specific genetic traits, such as color and size. Platys, mollys, swordtails, guppys, all can have 30+ fry every 30 days. This gets to be a lot of fish. If we take the bare minimums, lets add it all up:
30 fry each month x 2 females in a tank = 60 fry each month. 60 fish x 3 inches each = 180 inches of adult fish (they grow quick! My fry are almost the size of adults by 12 wks old) 180 inches of adult fish should have 180 gallons. You can see now how quickly this can get out of control if you aren't prepared for it.

One of my concerns is that the other fish will eat them. If they have enough hiding places, this should be less likely to happen, right? Plus, they're fast little devils! I have some large rocks and plants in my tank, but the tallest plant only reaches about halfway up. You mentioned that you have some floating plants in your tank - would you suggest I get some? My tank is very deep, so getting plants that reach all the way up has proved to be impossible so far. There is one fry that is loose in the tank - I spotted him hanging around one of the rocks. He did a good job of hiding from the other fish.
Remember, these fry are born with survival instincts in tact. After the numbers we worked with above, is it really such a bad thing if a few are eaten here and there? My adults don't eat the fry because they aren't hungry enough to do so. This is where the extra feedings and extra water changes come into play. The other thing I do differently is that once my fry are a few wks old, I move them to a tank of their own to allow room for the next ones. At present, my mollys as an example, the adults are in a 90 gallon tank with lots of decorations at all levels of the tank, are fed 3 - 4 times/day, and water changes every other day of about 30%. (yes, this makes for a high water bill, lol)

I feed my fish 2-3 times a day. I use flake food and have algae wafers for the catfish and plecostamus. I have a male guppy in the tank and he's a bit of a punk - he's been going crazy over the fry. I'm assuming he thinks they're treats, so I'm really afraid he's going to try and eat them. The platies don't seem to care much so I'm not as worried about them.
This also is normal and natural response from any of your fish. When breeding something like these fish, other fish are usually there to help with population control. If breeding is something you want to do, the fry are important to save and raise, then you want to put them in a tank of their own or simply keep them with their parents alone. A community tank is not a good place to expect to save a lot of fry. One other note here, when you know the fish are eating the fry, watch them at feeding times... so you aren't putting food into the tank that they really aren't eating. Fish can have huge appetites, but at some point there is a limit, and anything they don't eat will quickly pollute the water.
I have the Hikari First Bites food for the fry which they seem to love so far. Another concern about taking them out of the breeders cup is that they will not come to the top to eat the food. I don't want them to starve. The last batch of fry I had hung around the bottom of the tank, eating whatever they could find down there. Is that safe for them? If I get some floating plants, will they be more likely to come to the surface to eat?
yes and yes... fry will pick food where they can find it in "safe" places, and if these safe places span the entire range of the tank, then they will eat the best.

I change my water 1-2 times a week. With the increased feeding, I'm aware that this will also increase. My last concern is that they are going to get sucked into the filter. I have a Whisper filter with an extension tube to reach farther down the tank, but the end has large slits that the fry could easily slide through. It isn't near the decorations, so I'm guessing they wouldn't wander over to it. What do you think?
Healthy fry should have no problem swimming around the filter intake. My molly fry, only a day old, will pick plant matter from my intake, and that is a penguin 330 filter... much more powerful than your small whisper. My swordtail fry are often birthed under the AquaClear filter in my 29 gallon, and none has had any problems. I have been breeding swordtails for over 20 yrs now, and the only time I've ever had problems with any fry near an intake tube is when they were born unhealthy or with some form of birth defect. My females are always quarantined away from the others until I know they are done with any pregnancy issues that may already be in place. The don't become my breeding stock until I know for sure what male they were bred with. I've had females come home and get sick during quarantine, and sometimes the medications can do not so good things to a fry, both inside and out of the body. These fish were often used as feeder fish for others that I kept, and even of those... very few ever had a problem with any filter intakes.

I'm going to take the fry out of the breeders cup, but I would appreciate your input on the above, especially about how to feed them once they're in the tank. I've kept fish successfully for many years, but the whole breeding thing is new to me.
When you feed your adults, crumble some of the flake food into a fine powder, the fry will find and eat this on their own. This is when the water changes will need to increase, to clean up much of the powdered food that they don't/can't eat.[/b]

Once again, thank you so much for your help!
If you have any other questions or need help, let us know and we'll do all we can for you.

Dawn Moneyhan
Aquatics Specialist/Nutritionist
Juneau, WI
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