Double Aquarium Stands 30 gallon Bird Toys

Q: can this fit 29 gal tank?

Yes it holds two 29 gal tanks with room to spare, 6 inches on top and bottom, put board there to hold my air pump, put on tank on left and other on right to balance the stand have fun

Q: If the tank is too small for the dimensions of the stand, should you put a piece of wood as a platform?

I would not Recommend. If the Tank as wide as the Stand but not as long then no wood is needed. I my Self Have a 40gal that is the same with but short by 2in approximately in length to the Stand. It has Ben on there for 6 years no problems.