warm/cool-weather species switching

Hello!

I live in the North of Italy and here the weather is very hot on Summer (86°F) and cold during Winter (32°F).

I don't have a system yet and my plan is to create a small one in a green-house in my garden. Since the wide range of temperatures in my area, I was considering the idea to switch from warm to cool-weather species during the year (catfish/blackbass on Summer and trout on Winter). Obviously I'd need to find almost-mature fish instead of fingerlings.