Why Are My Molly Fry Dying One By One?

[pingu1997]

Hi, got a relatively new but cycled 180 litre tank, with 10 mollies, 2 guppies, 10 cardinal tetra and 3 platys.

2 of the mollies had babies 2 and 3 weeks ago

I fished out as many as I could, maybe 25 fry in total, and put them into a clip on nursery tank (I am cycling a smaller tank but it's not ready yet)

I feed the babies on powdered flakes about 4 times a day, and I change the tank water (about 20 PC) once a week. I test for ammonia and nitrite regularly and levels are zero. Nitrate 10-15 (ish) temp 76, PH 7.6, hard water.

Almost every day for the last week I have been fishing out dead babies. They go lifeless and sit on the bottom then the next morning they have lost their colour and are dead.. the adult fish in the tank all seem happy and not behaving oddly?

Is this normal or not?

Thanks in advance for any replies

Corinne

 

[KittyKat]

If the parents are inbred, and thus the fry do not have a good immune system and are not that healthy, then this is nothing unexpected. This is quite likely to be a contributing factor, if not the main reason, if you bought the parents from an LFS and not from a good breeder.

 

[OldMan47]

I see nothing inherently wrong with your arrangement Pingu. Mollies in relatively hard water having a pH in the range that you seem to have should do fine. If you have a sealed baby tank, that is your problem. The tiny space does not hold much water so it will go bad fast unless it is free to exchange water with the larger tank it is located in. Do not be misled by the small size of the fry. They produce quite a bit of organic waste for such tiny fish and need more care than typical adults the same size would to keep their water pure. You should not be losing any fry in a cycled tank setting with your water parameters unless maybe you have the temperature of the tank too high. Many people will run molly tanks much warmer than is really good for the fish. I have found that my own are quite long lived and robustly healthy at around 75F, 24C. My fry losses may be 1 or 2 fry from a drop of 30.

 

[anah2467]

Hi Pingu1997. I totally agree with Oldman47. I'm a newbie myself but luckily my frys are just doing great and thriving, getting big in their divider for now. No loss, so far thank goodness. I'm the same with you cycling a bigger tank for them frys, hence the divider for now. I'd figured the breeder box was too cramp for them and the one I bought was crap anyways. Also, your frys are mollies bigger than my platys they'll want more room to grow. Like me just an alternative, if you wanna try a divider visit your LFS and find a free flowing one.
P.S. My divider where the frys are is just like a separate tank..meaning I've got live plants and a decor for them to hide and some floating plants too. Had to make the food sink while they learn to swim up in their own. I made sure the hang on back filter is not on their side, don't want them to be suck up.

 

[pingu1997]

thanks for replies. I had wondered about both the inbreeding thing and the waste, of course the water flows from the main tank into the creche (as it is like a breeder net thing which hangs on the side of the main tank) but I did notice that old food and poo sits on the bottom, I have moved them already once into a clean nursery tank for this reason. Until I get the second tank cycled there isn't a lot I can do really. Hurry up tank number 2, your fry need you!!! Meanwhile I think another move and clean out the nursery, they do produce a lot of waste!!!!

 

[fish48]

sorry i got to say this inbreeding as nothing to do with your fry dieing

 

[pingu1997]

OK well I have moved the fry into a clean breeder trap and see if that stops them dying.... and I'll keep doing that every time there looks to be a build up of poo or uneaten food..... they aren't going hungry and they can swim up for their food...

I am cycling the second tank but it's being really slow despite me putting filter media from the existing tank in there grrrrr