Join Date: Jul 2010
Location: Outside Philadelphia, PA
I have used a 40 long like you are talking about. It was the same base as a 55 but shorter.
The tank looks nice, but it's far from ideal. Since the tank is only 12 inches front to back and it's not that tall, it makes it very difficult to aquascape. I'm not saying it can't be done, but it's really hard to end up with something that looks decent. Most of this also applies to a standard 55, but since you have some additional height, you have some additional latitude.
Since you want the "ultimate open space schooling tank" I suggest you look in to a couple of tanks that I think are much better options. Consider a 70 gal tank. It's got the same frontal area as a 55, but is 18 inches front to back. You'll get a lot better aquascape out of that. Think large rocks, driftwood and so on. Another possible tank is a 90 gal tank. It's got the same base as the 70 but a couple of inches taller. This may be more height than you want. Also be sure you can easily reach the the bottom and back of the tank, it can be quite a stretch.
Of course if space is not a problem and money is no object, something like a 125 would look fantastic, but I think you'd be far beyond your budget at that point.
One advantage you have with taller tanks like this is that you can put fish in and see them in distinct zones. For example, you can use hatchet fish, and the will stay close to the surface, then red tail rasbora and they will tend to stay in the top third of the tank. Then rummy nose tetras, and they will tend to stay in the middle third of the tank, and you have your usual catfish at the bottom. Of course at feeding time, juat about anything will go where the food is.