Molly breeding

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Aquarium Advice Freak
Apr 21, 2008
Montreal QC CA
i have a trio (1m 2f) of black molly,
and they are actively reproducing as soon as
the PH is stable for 1 week
the ammonia/nitrites/nitrates are under 0.5
also as soon as the water temp is stable at 27c (80f) for 2-3-4 days

seeing i just recently ended my main startup cycle, and they have already spawned 2 times, i was thinking this time to take some precautions so that the fry does not end dead again (first time due filter suction second due tank-mates hunger)

i am in need of a separator that can be dripped in the main tank (so that the water params stay stable = ph temp aeration) and where the mother can be put separated from the rest of the tank, and then when the fry have been layed, the mother can be removed and fry to stay in the separator

i am sorry if i am not explaining it exact enough, but honestly i have no ideea what to look for

i found a nursery that allows several mothers to be separated, BUT the nursery is out-of-tank

i found a in-tank one but there is no separation between the mother and the fry.

and honestly i'd hate to have to buy 100 nurserys when there is one that does all the job.
I have many mollies, platys and guppies in my 55 gallon tank and it is heavily planted with plastic plants and I have lots of fry. I am in the process of switching from plastic plants to live plants but as long as there are plenty of good places to hide and you feed them well, I have never had any trouble raising fry this way. Never had any luck using the breeder nets and such.
I've used breeder nets, boxes, cages and plants for my swordtails. Most of them are useless because the fry are smaller than the holes in whatever barrier I put up. Couple that with an infants very poor understanding of "large fish eat small fish" and it gets frustrating rather quickly.

The best bet is to put the female in another tank just before she gives birth and remove her right after. So far the best breeder type tank that I've had is a 1.5 gallon tank with a sponge filter. They're cheap, easy to maintain and you can throw them in a closet when not in use. Just drop the sponge filter in your main tank so it stays cycled and ready to go whenever you need it. The small size of the tank is no big deal since you're only putting a single adult fish in there for a short time, and it's more than enough room for dozens and dozens of fry until they're big enough to survive in the main tank.

Tetra Water Wonders 1.5 Gallon Aquarium Kit at PETCO
That's actually the one I use, though I got it at Big Als, there's dozens of similar tiny tanks out there. Stuff you usually wouldn't even look at because they're barely big enough for a betta.
Moving any preganant molly is hazardous to the young and more often than not contributes to stillborn or premature young. Having a well planted tank, artificial or otherwise will result in enough young to survive to increase your population. As to your cycling and all, I couldn't make any sense of what you were describing, but as your tank becomes more mature and stable then your mollys will do better. Bill
As someone who has kept livebearers, please believe me when I tell you that you will have plenty of fry over time. Do not put the mother into a small container to try to contain the fry. Let her give birth in the main tank and then move the fry yourself to a breeding net. You are going to end up with more than you can handle eventually anyway. That's what livebearers do in tanks. Try not to worry about saving each and every fry that you get as there will be more. There are always more.
i do not have troubles understanding the way nature works (as someone here said ... big fish eat small fish) but my wifey does.

she'd get extremely sad every time on of the small fry is no longer in sight.

that is one of the "why i do not have bushy plants" in my tank. because as soon as she cant actually see one of the favourite fish, she gets upset because she thinks they died, so i have to have all fish in eye sight at all times.

that being said, i'd rather grow the fry and have them delivered to a LFS (or to my friend that has piranhas ... without wife to know) then to actually miss them in the tank.

BTW with life bearers it's actually VERY easy to make sure they do not reproduce.
a temperature oscillation of 1-1.5-2 degrees will prevent the male from having the urge, so from that point of view i am all set,.
Can you explain the temperature oscillation theory to me? I don't believe that will work based on my experience.
i tested this when i was young, abt 14-16 years of age, and truthfully it worked

when you have a stable temp for over a week, and you do a spike of 3-5 degrees (colder) when you do a PWC, the molly and guppy instantly start breeding (having sex to be more exact)

from that day in 10 days you can remove the mothers in breeder tanks, and leave them there for the rest of the gestation period.

i populated a HUGE tank this way in about 4 weeks, and then i populated the whole neighborhood with guppy ;P
So your theory is that if temperatures are held within minute swings of 1.5-2 degrees, no breeding takes place? That's interesting, but how can you test that without multiple thermometers in the tank as well as testing the temperature of your water the whole time you are adding it to the tank?

I don't think you can stop livebearers from breeding as long as they are healthy. I've neglected my tanks in the past and breeding and birthing still occurred. You may be able to encourage breeding with the temperature fluxes as you noted, but that is not property may not be commutative, meaning it wouldn't work both ways.
i am only saying that when you to a major temp spike (aka 2-3-4 degrees drop, then slowly go back to normal) the molys and guppy are frenetically reproducing.

that said = increased reproduction rate for a short while (you are actually sure that the female have been fecundated during this few hours worth of time)

i am not sure if you would actually KEEP them from reproducing if the temperature fluctuates a lot.
edit: sidenote, when i said 1.5-2 degrees fluctuations i did not mean every minute, but every day.
this can be easily do-able if you setup your thermostat at 24C and put the tank somewhere near a sun area
during the day the sun will heat the tank a couple of more degrees then usually.

from my experience with molly, they do not do any repro if the tank conditions aren't stable, but then again i am not a specialist.

if this didnt answer your question, i am afraid that i did not understand your question
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Floating plants

I have some Mollies and Platies in my tank, and the Mollies love to eat baby Platies. I don't like the way artificial mesh nets and breeder boxes look but even with a lot of planted plants I was losing fry.I ended up buying lots (and lots) of plants and letting them just float on the surface. I mixed the real plants with some dense, "furry" plastic plants, and cut up or bent them to create a kind of floating ring pushing the live plants down. It was a floating mess of real and fake plants with a small "lagoon" in the center that was about a half inch deep and was shielded from the adults on all sides and beneath. The babies could swim freely in open water (surrounded by a leafy perimeter), and could dart back into the heavy growth around them if a curious adult tried to poke its head through. I haven't lost one yet, although having several inches of plant life floating at the top does block out a lot of the light.
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