If possible, a small breeding net would save many. They hang on the tank edge inside, if there is room. Might also try a small floating breeder box. I doubt there is room for a box that hangs inside.
Marina also makes a box that hangs outside, and uses the tank water to circulate, via a bit of tubing and an air pump. Won't look amazing, but will save fry 'til they are larger. They make 3 sizes,, the small or medium may fit.