Mollie and Swordtail Fry

[Wat2Go]

My son's mollies (in a ten gallon) produced fry and loads survived.
As my male swordtail died and the female was pregnant, I decided to set up the 29gallon as a fry tank.
So in it right now a mommy mollie with about 20 babies and a mommy swordtail with about 10 surviving babies. Mollie babies are about 3 weeks old, swordtails about a week. They have lots of places to hide.
How long can I keep them in the 29 gallon? I only want to keep a male swordtail (hopefully one of the fry is male) and maybe 2 females. I don't need any of the mollies. All the rest - provided they survive - will go to the LFS and friends. We would like to enjoy them for as long as is ok though...
At what age do fry produce too much of a bioload, so when is the time that I really need to take them out?

L.

 

[jaylin]

Best way to determine that is to test the water.

I'm not trying to be smart, but all tanks can be different based on what's in them and what's not in them. The size of the fry, the number of fry, your feeding habits, their eating habits ...

So, keep testing the water and when it starts getting difficult to stay ahead of the nitrates, it's time to move some out.

 

[Virtuoso2K12]

first you'll have to take out any babies you want unless your tank is planted well with hiding place for the frys,you have a filter that may catch the frys?

 

[Snakes]

It is advisable for them to be taken out so that they wont get eaten and in that way u can feed them without them being scared to come out of hiding places

If Possible it would be easier to remove the adults than catching lots of fry

 

[robbob2112]

It is advisable for them to be taken out so that they wont get eaten and in that way u can feed them without them being scared to come out of hiding places

If Possible it would be easier to remove the adults than catching lots of fry

I'd have to disagree here... Mollie and swordtail fry are fast little guys (I've seen them survive in a cichlid tank for several days because they can turn on a dime) and pretty bold after only a couple of weeks... at the same time the parents will tend to ignore them in favor of the slower moving food you feed them.

If you like you can put a sponge on the filter intake to keep them from getting sucked up... but again after a couple of weeks they seem to know what to avoid and have no trouble staying clear of my intake.

If you find a LFS that will take them you will be lucky, most don't want mollies at all, or if they do they won't take them until they are a sell-able size (9~12 months old)... I personally use my fry as feeder fish for my cichlids, safer than the store bought feeders, and I would like to think healthier....

I'd have to agree with the earlier comment.. the only way to know is to test the water and move them when the nitrates grow to quick to stay ahead of them... live fast growing plants can help with this as well as give them a place to hide and feel safe... and the inevitable algae growth you will see from the nitrates will provide a food source for them to graze on.

 

[Wat2Go]

Thanks!
Will keep testing.
Fry that is in there now won't get eaten anymore, they are too big and too fast (almost 4 weeks and almost 2 weeks), plus there are many many hiding places (long grass on the bottom of the tank, the fry only "rises" if there is food!).
My LFS luckily will take them as of about 3 months...

 

[OldMan47]

A good way that I have found to judge bioload of fry is to think of the fish it would take to eat the food I am feeding. You already know that your 55 gets a lot more food than a 29 and it gets a lot more than a 10. That is because you have carefully stocked the right levels of adults in those tanks. If you find that it takes more food to feed the fry than you would expect to feed a tank that size, you have probably crossed the line to overstocked. After all, the source of ammonia and nitrites is fish waste that ultimately comes in as fish food. If you go all the way back to the food, you can often get a feel for how you are doing.