How large is your main tank? The reason I ask is the tank size can have a large impact on your cuttles. Too small and you can get a lot of aggression and depending on the infrastructure of the tank and turnover rates your animals could be at risk. If the tank is too big when you feed them live shrimp the shrimp can get "lost" in the tank and it could be difficult for the cuttles to find them.. which is particularly an issue for flamboyants. If it's possible to hook up a 10 gallon to your main display system that could be adequate for these two cuttles.The tank that they are living right now is an extra tank I made for them which is connected to the main tank since I thought minimising the area can boost their relationship. If bigger tank does help, I will put them back to the big tank. But since I wasn't sure if they sre male and female, I don't know should I order an extra one