Thanks im not sure how many gallons it is never calculated it up. I love these rays had them for about 4 years. there like dogs, they come to the surface and eat right out of my hand. If im sitting or standing with my back turned to the tank they will surface and spray water on me. I do have another tank with rear overflows that is a little over 300 im thinking about moving them over to. Im not a huge fan of the plumbing coming up threw the bottom of the tank but it doesnt seem to get in there way they never run in to anything.