Most likely, fish can die during giving birth just as much as we can as its a very stressful proceedure especially for a first time mum fish.
Creating a stress-free enviroment will help prevent these bad consequences, heres some factors you need to take into consideration;
a. Females will often get harrassed by other fish when they are trying to give birth, this is normal behavior from the other fish as they will try to eat her fry as she gives birth to them and the male fish will eagerly try to mate with her as she becomes available.
As a consequence this is very stressful for the mother fish and providing lots of planting for her to hide in and enough space will help avoid this.
If the harrassment is realy bad though it is advised you move her to a breeding net/trap or empty fry tankso she can at least give birth in peace. Also if you have an agressive fish like tiger barbs in the tank with her, move her to somwhere where she can give birth in peace as soon as she starts going into labour, these fish like tiger barbs will undoutably over harrass her as they have a reputation too.
b. Creating a stress free enviroment; if your tank is cycling/newly setup the fluctuating water quality conditions will be very stressfull for any pregnant fish, particually one that is trying to give birth, so keeping good water quality conditions via by doing lots of 20-30%water changes daily with dechlorinator is more than essential in this scenario. Keeping good water quality via water changes is a must in any scenario as if there are issues with the water quality this will make the tank conditions stressful for any fish, pregnant or not; you can find out wether your water quality is good by montering the toxins ammonia and nitrites and nitrate levels weekly via test kits bought from your local fish store.
So, you have managed to secure good water quality for your fish. After checking that your stocking levels and gender ratios between your fish are correct and need no changing, let us turn to the enviroment of the tank itself.
When a fish is trying to give birth, she will instinctively try to find somwhere in the tank where she can hide and do this in peace. Providing some densely planted areas and a couple of caves in the tank is very nesarsary for her to do this, we are not talking just one or 2 plants and a rock in the tank but somwhere that she can realy hide from the other fish and cannot be seen by them or you. When the fry are born they too will also instinctly hide in these hiding areas away from the mouths of other fish, the more hiding places the tank has the bigger the survival rate of the fry and the less stressful giving birth to them will be for the mother fish.
c. fry/birthing tanks and breeding nets/traps; if you have a decent sized cycled spare tank for the mother to go in that is not inhabited by other fish, you can avoid these processes to a certain extent(although good water quality and a certain amount of hiding places for fish is a must for any tank). A decent minimum size for a birthing tank is 5gallons and so is for a fry tank, if you have more than one pregnant female in a birthing tank this is no better than keeping them in the main tank together though.
It is good to have a breeding net or trap at hand in any situation although these themselves can be very stressfull for the pregnant fish due to the lack of space, try not to keep a platy/guppy sized fish in a breeding net for more than 4days and a molly/swordtail sized fish in it for 2days as anymore time than this will make the whole proceedure worthless and more stressful for the fish- more than one fish per tank/net/trap is also totally unaceptable.
d. food; feeding your pregnant fish lots of high protein foods like bloodworms/tubifex/daphinia/krill(freezedried, frozen by thawed out or live) will help give her some extra energy to help her cope better with the pregnancy and birth too.
Follow these directions and it will make the whole pregnancy and birthing process much less stressful for the fish and increase pregnant fish survival rates alot

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