Now you can make water changes in the larger tank. The system has two additional advantages. When raising large spawns, you have the biological filtration capacity of two sponges working. I can maintain a fairly dense population of fry without compromising water quality. The spawn experiences no shock due to water conditions.
Some fish are bullies and other fish are victims.
If the harassment reaches the point of endangering health, it's good to separate them. For reasons of economy, I use partitioned tanks to keep breeding pairs. Commercially available dividers, a flimsy collection of plastic flanges, metal hooks and a plastic sheet with tiny holes, are less than desirable for several reasons. Commercial dividers are difficult to set up and keep in place. Many people cement the flanges against the glass to hold them in place.