No these 2 are pretty good together....they only spent 1-2 hours in my divided 55 before I moved them into this 90. She loves laying in a certain area of my DIY BG. I took him out because I was gone a couple days and I wanted to be safe.
yeah adding a sponge or mesh filter over the intake is a good idea and you should do water changes to keep the water quality up, obviously avoid sucking up any babies =D adding methylene blue is also good to add to help keep fungus at bay, especially during egg and fry stage. It's totally safe for eggs and fry.
This is my fry tank...I've had one of my rescue flowerhorns in it for a couple weeks....I drained all the water but cleaned the filter in THAT water. I filled it with the water from the mother's tank that the fry came from. Hopefully they can grow out in this tank for a little while. You can't see it too well but all sides, back, and even the bottom are lined with blue background paper.