I have had my gouramis for quite a while and the large male has always been troublesome , killing platys and guppies and then last night my female gourami, I have changed scenics around but issue carries on so I finally isolated it from the rest of the fish so it won't harm them anymore , I spoke with the fish shop and they said I can bring it in and exchange it but what would I take in down in or would I have to go and get a bag from them and then take the fish in but the shop is far away from my home?