Balloon Molly Fry = High Mortality Rate?

[trickyspark]

I have a tank of Balloon Mollies and Swordtails. I inherited the Balloon Mollies from a friend that was considering throwing his fish out.

My female swordtail and one of the female mollies gave birth within a few days of each other.

I collected the mollies in one breeding cage, and the swordtail babies in another.

They were both fed the Tetramin fish flakes (crushed finely) and the Spirulina type (crushed finely as well).

Right away I notice a difference, 90% of the mollies lay on the bottom of the breeding cage (floating cage kept in original tank) so I put some of the aquariums gravel in there for them to hide in. This was on the first day I found them, they couldn't have been more than a few hours old. They die about 1 per day, then 1 every other day, then with increasing amounts of time between deaths. There were around 8 left when I put them in a small 10 gallon tank that was cycled and had 4 cory's in it I was trying to breed.

I found the female swordtail dropping babies, I put her in a second breeding cage that had small holes for the fry to drop through. She had 14, I accidentally squished one (i feel like crap) when removing her and the seperator. This leaves 13 when I move them to the 10 gallon tank.

I notice fewer and fewer mollies over the next few days, the fry were quite larger than the swordtails. I count 7, then 6, then 4, now 3 are left and they are quite big and healthy looking. Although the 7 I moved were bigger and healthier looking to. They were also the ones that didn't tend to lay in gravel in the breeding cage, almost all of those had died before being moved.

Every one of the swordtails is still alive.

Is it normal that ballon molly fry die easily. They seem to just lay down and give up right at birth. The swordtails in the same tank haven't went to the bottom of the tank yet. I haven't seen the cory's bother any fry. I keep the cory's and the fry well fed. The water tests fine. I have not added salt due to the cory's that were already in the tank, and the pleco that is in my larger tank.

The mollies that died earlier on acted like they were to heavy to swim, they'd struggle up about an inch and fall back down. The ones that lived longest swam about as they pleased.

Is the salt the key? Or could it be the imbreeding I hear is such a problem with balloon mollies?

 

[puppyjess123]

Well I had this once with sailfin mollies and they all died one by one like yours and it was because the mother was not healthy. (Had callamous worms) Is she okay?

 

[OldMan47]

Salt is not at all the key, but it is a common excuse. I am assuming that you know what a cycled tank is so won't ask about ammonia and nitrites.
What are the water parameters? I am especially interested in water hardness and pH. All of the common livebearers, which includes swordtails and especially mollies, need fairly hard water with a moderately high pH. A cory breeding tank is likely to be intentionally maintained at very different conditions than what would suit a molly.

 

[trickyspark]

Double post.

 

[trickyspark]

These parameters are almost exactly the same in both tanks, the ph may be slightly under 8 in the first tank i had them in due to the color being just a little lighter than 8 on the color scale.



Their is one of those long airstones that runs the length of the tank in the back. I have the default filter that came with that tank, it uses a carbon cartridge to clean debris and also has a sponge filter for biological purposes. The carbon cartridge was replaced about 2 weeks before I added the cory's, and about 3 weeks before I added the swordtail and molly fry. I am unsure which female molly gave birth as there are 4 females and 1 male. The females are all big and pot bellied, and look the same as they did when I got them. They act fine, pooing and eating as far as I can tell are normal.

Here are the parameters I was able to test for in the cory tank. I haven't intentionally added or changed anything to prepare for them.

The temperature is 77-78 always. My ammonia was 0ppm. My nitrite was 0.3mgl. My ph is 8. My carbonate hardness is 8 and my general hardness is showing up as 3. I guess this is bad as it indicates 6-16 GH is what you need. The KH-carbonate was spot on though. I tested my tanks and all 3 have a GH of 3. The molly are the only thing I've had die except 2 swordtail and a few ghost shrimp in over a year.

Any ideas on the hardness of 3 being the problem and if so how to fix that?

 

[OldMan47]

My mollies are thriving n a GH of about 8. My KH is similar. To me your nitrites look a bit high and the GH is showing fairly soft water. Mollies like their water hard which is why some people think they need salt. Salt does bring the mineral content up but in a funny direction. If your tap water is harder on the GH scale, I would do a large water change. If not, I think a water change to bring down nitrites is also in order, but you might get away with only 30% for that.

 

[trickyspark]

When I said the amount for nitrites it was based off the color chart with my test kit with < 0.3 being the lowest reading (yellow color) orange is >0.3. I had a faint yellow which is the lowest reading on the chart. I guess maybe I shoulda have said less than 0.3. Maybe I need a more specific test?

My tap water is what I put in my tank (after adding dechlorinator). I put some straight from the tap in a bottle and mixed in some dechlorinator, let it set for about an hour and tested it. It was a GH of 3 just like my tanks.

I posted a little pic.

I found something in my Doctors Foster & Smith catalog that was called a RO water conditioner, are these safe to add? It's supposed to add trace elements and such without affecting other parameters such as PH and whatnot.

Gonna see if I can get a more accurate test kit and maybe some water conditioner tomorrow. I am using the Tetratest Laborett at the moment.

Thanks for putting me onto the hardness. I've had aquariums for about 2 years, and only ever bothered checking nitrites, ammonia and PH.

 

[OldMan47]

I have used a product called RO Right and it seemed to work OK. I wish I knew what was in it though. That was back when I thought it a good idea to fill the tank with RO and the chemical mix. Since then, I have learned my tap water is great for most livebearers so the RO has been relegated to drinking water and a breeding tank for cories where I use mostly RO with a touch of tap to bring up the mineral content a bit. The GH from my tap is quite high, over 15. I use my plants to pull minerals out of the water and drop my TDS quite a bit lower than tap without using RO except to top off a tank that is a bit low on water. The wife says the fish are getting thirsty.

 

[HCpetraitis]

I do the same for water sometimes. The tap water I have has some salt in it that my mollies seem to like.