I have a hystrix couple in a 180 gallon tank, it works good and there is no issue. But i am debating with myselfe if they should go in the 1200 gallon tank with the other rays. The hystrix rays will be the smallest in there, and their tankmates would be 2x motoro males, 1 sp peru male, 1 sp peru female(BIIG), and 1 Motoro female. What do you guys say?