I used 3/8" oak dowel rods and glue hold the frame together. No nails or screws used.
The 2 X 4 frame which holds all the weight of the tank.
This is what it looks like after I place the 1/8" veneer oak plywood skin over the frame. This cabinet holds a 29 gallon fish tank.
The complete wood top assembly can easily be removed for cleaning the tank. The top is hinged for easy access for feeding.