Wasn't the brand name "MetaLife Tanks"?
I remember those very well, they were made in 5-55 gallon sizes. Very popular in the 1960's. I remember that if you ever emptied them for cleaning and then refilled them they would start to leak. So if you emptied it out and cleaned it, you'd be best off by resealing it before refilling it. I read somewhere recently these tanks are now in high demand for $$$.