New Member
Mar 19, 2019
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this tank is seeing a lot of love. It’s spring, I guess!! Should I mark today as day one? And is it a couple of weeks or 60 days of pregnancy? Either way, updates to follow! (slight feeling this female molly won’t make it, though...she doesn’t look too active...does mating make the female seem a little chill and kinda just hanging out?)


Fish Guru
Jan 26, 2008
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Perth, WA
In the wild, female livebearers hang out in large groups consisting of between 20 & 50 (but sometimes up to 100 or more) females. These groups have a pecking order with the biggest most dominant female ruling the group and she has a group of girlfriends who back her up. All the other females live in the group but are lower down the pecking order.

The groups of females move around rivers and waterways looking for food and places to hang out. As the groups move around a few males follow the group and try to breed with any females.

In the confines of an aquarium, the males will constantly harass the females and try to breed with them. This puts undue stress on the females and if there are too many males constantly pestering the females, the females can get sick and die.

If you want a group of males and females then have 1 male and at least 6 females (preferably 10 or more females per male).

Female livebearers can carry up to 6 sperm packets from breeding with males and they use 1 sperm packet to fertilise each batch of eggs. The gestation period (from the time she fertilises the eggs to when she gives birth to free swimming babies) is about 1 month. After which she will fertilise another batch of eggs using another sperm packet. This allows female livebearers to produce young about once a month for up to 6 months without any males being present.

Your female molly looks like she has gill flukes and appears skinny, which would indicate intestinal worms. You can use Praziquantel to treat tapeworm and gill flukes. And Levamisole to treat thread/ round worms.

You treat the fish once a week for 3-4 weeks. The first treatment will kill any worms in the fish. The second and third treatments kill any baby worms that hatch from eggs inside the fish's digestive tract.

You do a 75% water change and complete gravel clean 24-48 hours after treatment.

Treat every fish tank in the house at the same time.

Do not use the 2 medications together. If you want to treat both medications in a short space of time, use Praziquantel on day one. Do a 75% water change and gravel clean the substrate on day 2 & 3. Treat the tank with Levamisole on day 4 and do a 75% water change and gravel clean on day 5, 6 & 7 and then start with Praziquantel again on day 8.

The water changes will remove most of the medication so you don't overdose the fish. The gravel cleaning will suck out any worms and eggs that have been expelled by the fish. Repeating the treatment for 3-4 doses at weekly intervals will kill any worms that hatch from eggs. At the end of the treatment you will have healthier fish. :)

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