i have kept FRT with tigers works fine for about 6 months then that cute little FRT will turn into a killer everyone thinks their FRT will be diffrent but turtles eat fish their for turtles are not a good mix with ANY fish
i know someone who had 5 x 12inch ST with a 14inch MBU he didnt keep them in the same tank for long
at the end of the day they are your fish your turtle but i wouldnt risk it