To tell the truth turtles and fish don't mix well
As for red ear they need to come out of the water meaning your tank will have a very low water level
I thought if you gave them plenty of room it may work so when I setup my 1000
gal I got a Fly River turtle that is fully aquatic they are very cool but very expensive
It worked fine for about 2 months then the turtle started taking chunks out of fish
Fast moving fish may work but they will get picked off one at a time at some point
The other problem you will have is turtles produce a lot of waste which may not affect the turtles but the fish will hate it
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