the tank is 300 litere plus an additional lamd part. I have very strong and good filtration and would like to keep some fish into it. Emydura are non agressive turtles but carnovorous. I thought about rainbow fish. some do that because its same habitat. But they seem ideal size for food and aren't very fast.
so ~80 gallons? Uhm, I personally would do cheap quick fish, such as tetras, tiger barbs or other barbs, or even some convict cichlid or something. Idk you could probably do many things, but just be prepared to lose a few.
You think that could work? Emydura are day time active. The rainbow fish too. So at night there would be no danger for the sleeping fish, because the turtles sleep as well.