Molly fish are pretty hardy and can handle a wide range of water types. It would be a good idea to keep the water temperature at around 78-82 degrees. When Molly fish are about to deliver they usually hang out around the heater. As for the filter, it doesn’t matter much. As long as you find a way to keep a stable ecosystem for her. Mollys usually deliver 20-50 (mollys are live bearers) fry depending on their sexual age, and unless you plan to sell or keep them all I wouldn’t worry much about them. The fry will naturally find hiding spots, however adult fish can be pretty good hunters so it’s not a bad idea to separate them for their survival( natural selection is a thing in nature) If you plan to keep the fry alive it would be a good idea to grind your feed up into a powder form so that they can consume it and grow. If you’re not familiar with how to determine the sex of the Molly, here’s a simple rule: males are usually darker to almost black and have a much longer dorsel fin that is taller and almost reaches the tail. All in all, it’s not much to worry about and I wouldn’t get emotionally invested. Molly fish breed like crazy and will even breed with their siblings. But to keep momma happy make sure she has heat and good water conditions. Also wouldn’t be a bad idea to add in a little calcium to the substrate via. Crushed egg shells. I hope I helped!
