I'm interesting in rays. I don't think I'll be able to get one in the near future or anything but it doesn't hurt to do some research. I was wondering.....could you keep a ray in a 40 gallon breeder? I'm assuming rays don't need tall tanks that they need wider tanks. If rays can be kept in a 40 gallon breeder could you keep two? The ray I have in mind is the Potamotrygon Leopoldi but like I said earlier I won't be getting one for a long time probably. Just doing some research before hand. Thanks.