Tank size for motoros is enormous...very minimum of 8 feet by 4 feet...24 to 30 inches tall is fine. I run my tank at 82. Run your pH at whatever your tap water is because if you play with your pH all the time trying to hit some magic number you'll do nothing but stress your rays. Anything between 6 to 8 is fine as long as it's CONSISTENT. Diet is pretty simple, tilapia, market shrimp, squid...any meaty sea food chopped to bite size pieces is fine. Best to prepare a large amount, mix vitamins like seachem nourish and freeze in ziplock baggies. Flatten out the baggies to about 1/8 to 1/4 inch thick so you can just break pieces off to thaw and feed. Pups can be fussy, so chopped nightcrawlers work well if they refuse chopped seafood. Probably best to concentrate on just rays before you attempt to keep other fish with them. The most important thing to keeping rays alive is water quality. It must be pristine. A drip system is a must, and a cycled filter. Sump system is really the only practical filter for a large system. Motoros get very large, females exceed 30 inches measured across the disc. Good luck!!
