They sure look easy enough to make, but don't do what I did my first time....
go slow, allow plenty of time for the joints to cure, and my next one will have steel angle iron in each corner and all around, with a neoprene layer between the steel and the wood. If you are going to make wood back and sides you might also consider steel strapping, or even a steel plate to further strenghten the wood.
My last big tank was welded stainless steel bottom, back, and sides with a glass front, and it was 1" thick glass if that gives you an idea of how large it was. It always freaks me out to go visit the guy I helped build it and have a 4 foot shark swim up to my face when I walk in the front door!