I'm looking to get a ray for my tank. I'm looking for one of the smaller species like a male motoro, male marble, male MMxMotoro, retics, etc. My question is how will it work with my current stock? I have a fl gar, clown knife, and polypterus ornate in a 180 gallon tank with an fx5 filter. I know the rays might/will outgrow my tank but if I can't upgrade then I will rehome them.