Ok so no to the ray, and just one shark the shark my LFS can get in is chiloscyllium plagiosum, i want one just with some angels and tangs etc. i have herd some where else some one say they would have a 6mx2m tank to stick to the 6x2 rule, is that necessary. i will enlarge it from the min tank size BTW the largest i could fit would be a tank with a 400cmx180cm how ever that would cause a few problems and i would prefer to go with something around the 300cm or less on the length, so would a 300x180x75(H) cm be OK. but i have just herd they need round tanks, is this needed? as the only cylinder sized tank i could fit would be 240cm in diameter.