man even a 75 is way to small its only what 18"wide and not more than 3 feet long how long is that ray a good 24" prob it needs a tank atleast that even if it is temp. you need to consider whats best for the ray.....mabye you should give it to someone with a pond until you get yours finished then get it back...cause thats just not fair to the ray...whateva you decide good luck....o and if you need a big tank for a good price check out www.glasscages.com