Baby fry...need advice!

Hi all!

My mickey mouse platy has birthed her fry this morning. I could probably see around 15 to 20 fry in the birthing net, and wasn't sure she was done yet. I've come to check on her progress and I think I only see about 10 maybe less? So I was worried she was eating them so I've popped her into the main tank again. Firstly, is there any way to know when they have finished giving birth? And secondly, since I've put her back into the main tank, my molly is showing some real aggressive behaviour toward her. He is swimming close to her whilst fanning out his dorsal fin to make himself look bigger and flicking her with his tail. Is there a reason for this? Thanks in advance. X

She likely was eating fry, so it's good that you moved her back out of the net
It can be hard to tell when they've finished birthing. they can sometimes stretch it out over a couple of days. Your best bet is to check the tank a few times a day for any new fry, then scoop them up and place them in the net with the others to keep them safe from the adults.

The molly chasing her - hard to guess without seeing it, but fish can seem to sense when another is in labour, and it's not uncommon for them to follow the labouring mother around to get a free meal of tasty new fry. Sounds grim, but it's a part of nature. He might also be feeling territorial, and taking it out on her since she 'reappeared' in the main tank.

I wouldn't move her again if you can help it, she's already been through a lot, and every move from net to tank or vice versa, or to a new tank, increases the stress on her and could weaken her enough to make her sick. Better to risk losing a few new fry to other fish than to lose the female, you know?

A lot of plants in there, especially floating plants or fast growing stem plants like elodea can help. They give the mother a place to hide, and a hiding spot for new fry to have a better chance of avoiding being eaten. Fry naturally hide when born, and they tend to go for dense planting, or try to hide down in the substrate if there are no better options. Fake plants work just as well for this purpose as live ones. My first batch of guppy fry were hanging at the surface, and my real plants were not yet tall enough to reach the top. So I bought some cheap silk plants with a lot of leaves, suction cupped them to the side of the tank at the top, and it made an awesome fry nursery. The fry just moved around the leaves to hide when an adult ventured in there, and the fry didn't need to come out out of hiding to eat since I fed the adults at one side of the tank, then sprinkled finely crushed flake food in the fry nursery.

If you don't have much in the way of planting for hiding, and can't get anything yet, try doing a water change on the tank. Remove that male molly into the bucket of water you removed for a few minutes, and re-arrange whatever decor you do have in the tank. Top up tank with fresh declorinated water, then pop him back in, and it'll look and feel like a new territory to him, which might help take his mind off the female platy. Even better if you can arrange wood and stones etc to make more hiding spots and break lines of sight. Try feeding something like blanched courgette, or a food tab that they can spend some time picking at, to keep them occupied and give the female a break to recover.

If he still persists in chasing her after all that, and she's becoming exhausted and stressed, one of them will need to be removed.

It's most probable she ate her fry.

Floating plants like Salvinia or Frogbit can help the fry stay safe from those hungry adults.

For some reasome when they are in a fry net the mothers will eat their young as other members stated. I had a platy give birth about two weeks ago in my QT tank and she and the male platy seemed to leave them alone. I still move 8 of the 13 fry to a fry net to be safe. I did noticed the male start chasing fry a few days later so I moved the adults. I have the fry in the tank with a shrimp and some snails and they seem to be doing good. I feed them ground up bug bites flak food.